SEO Process

SEO vs. SEM: The Definitive Guide for Search Professionals 

Nick Eubanks
Last Updated: Mar. 19, 2024

As SEO professionals, we know the devil’s in the details — and the line between SEO vs. SEM is more than just semantics.

It’s all about organic growth and paid visibility — and what could be more important when we’re battling Google? Especially when you’re trying to hit those SEO KPIs

SEO and SEM are familiar terms to us, but do you know how the two fit together, and which one you should choose for your site and your goals?

Let’s take a careful look at SEO vs. SEM, why it’s essential to know the difference, and how to pick the right one for your situation.

What Is SEM and What Is SEO?

The primary difference between SEO vs. SEM is that SEO focuses on fine-tuning a website to get free organic search traffic. On the other hand, the goal of SEM is to get traffic from both organic and paid search.

For example, Google’s SERPs are divided into two sections: paid search results and organic results.

Google Search Results

SEO optimizes your site to rank higher in organic search results.

Google Search Results SEO

You can also use pay-per-click (PPC) advertising to get your website into the paid area of SERPs.

Google Search Results PPC

Right now, I’m betting you probably spend a lot of your time on SEO, focusing on ranking in the organic results. You might also venture into SEM, using both SEO and PPC to get traffic from search engines.

Technically, SEO best practices fall under the broader umbrella of SEM.


Now that you’ve got a basic understanding of these two terms, let’s dig deeper into the biggest differences between SEO vs. SEM.

An Overview of SEO

SEO optimizes a website to make it more visible in search engines and earn more organic traffic.

The four main categories of SEO are:

  1. Off-page SEO: This involves activities outside your website that affect rankings. The most common off-page SEO technique is building backlinks from other websites.
  2. On-page SEO: On-page SEO is optimizing elements on your site for specific keywords. For example, you can include keywords in your content, images, keywords, and meta descriptions. How do you find just the right keywords? Check out our list of the best keyword research tools.
  3. Technical SEO: This deals with the website’s infrastructure. With technical SEO, your job is to ensure search engines can crawl and index your site efficiently. So you’ll make sure your pages load quickly, your site architecture is correct, and there are no 4xx errors.
  4. User Interaction Signals: How does Google know if your page is a good match for someone’s search? It can take cues from your users by watching click-through rates, time spent on site, and bounce rates. To influence this part of SEO, optimize your pages and ensure they’re an ideal fit for people who land on your site from specific keyword searches.

Local SEO optimizes a website to increase visibility in search results for local-specific queries. It targets users in a specific geographic area and helps businesses be more visible to local customers looking for their products or services.

From meta descriptions to internal linking, Semrush’s Site Audit tool will give you a complete picture of your site’s health and offer actionable recommendations to improve your SEO.

Semrush Site Audit

An Overview of SEM

Remember that SEM is an overall term that includes SEO — so everything I described for SEO applies here, too. 

But SEM also includes paying for visibility on SERPs. PPC is a common part of SEM. With PPC campaigns, you can rank above organic results in SERPs, but you pay a fee each time your ad gets clicked.

When you search for “meditation apps,” for example, Headspace shows up first in the PPC results and first in the organic results:

Google Search Ad

But SEM isn’t just limited to PPC. These can also fall under the same umbrella:

  • Display ads are visuals that appear on a wide variety of websites. They can be static images, GIFs, or even video ads. They don’t appear on search engine results pages but are part of the broader SEM strategy because they target users based on their search behavior.
  • After someone visits your site, remarketing strategies enable you to show ads to that person as they visit other sites around the web. Yep, sometimes it’s creepy, but the idea is that you’re reminding users of their interest in your product or service and trying to get them back to your site so they can take action.
  • Direct advertisement involves purchasing ad space directly from a website, rather than going through a third-party system like Google Ads. For example, you might negotiate directly with a popular blog in your industry to have an ad for your site appear on their site.

Need that in a nutshell? 

Here it is: 

SEM combines the power of organic reach (through SEO) with paid strategies (like PPC, display ads, remarketing, and direct advertisement) to give you a comprehensive approach to search engine visibility.

So if you want to pay for search traffic as part of your SEM strategy, you might wonder what’s involved in that process. 

Here are the basics:

  • Start by identifying the keywords you want to build your PPC campaigns around. Semrush offers a number of helpful keyword optimization tools — more on that below.
  • By bidding, you set the maximum amount you’re willing to pay for a click on your ad. The actual amount you pay might be lower, based on competition and other factors, but your bid helps determine your ad’s placement relative to other advertisers.
  • Targeting involves selecting specific demographics, behaviors, or contexts where you want your ads to appear. By refining your target audience, you ensure your ads are shown to the most relevant users, increasing the likelihood of engagement. You can target based on factors like age, location, interests, search queries, and more.

Semrush’s Keyword Magic Tool can help you identify the right keywords to bid on in your paid ad campaigns.

Inside the tool, enter a word or phrase that’s relevant to your site, and hit “search.”

Semrush Keyword Magic Tool

The Keyword Magic Tool will display potential keyword ideas for your PPC campaigns. 

Semrush Keyword Magic music

Not all of these will be a good fit for your campaigns. In general, choose the words or phrases that are most likely to convert. Do this by looking at keyword search volume, keyword difficulty, and CPC.

The Ads History tool in Semrush provides insights into your competitors’ advertising strategies, helping you identify new opportunities, streamline your campaigns, and save time and money.

Semrush Ad History

Read our Semrush review to learn more about the platform’s extensive PPC features.

What Is the Difference Between SEO and SEM?

Let’s get clear on the differences between SEO and SEM. 

Most of our focus will be on the primary differences between SEO and paid traffic, but remember that SEO is also a part of SEM. Many SEO communities also discuss SEM. Let’s take a deeper look at what sets them apart.

SEO vs. SEM: The Timeline for Traffic

SEO is a marathon. Even if you’re an experienced professional with a reputable SEO business, it’ll take time for you to bring in traffic, particularly if your site is new and you don’t have a lot of backlinks. 

It can even take years before you rank on the first page of Google. And even with consistent effort, there’s no guarantee you’ll make the coveted top spots for highly competitive keywords (or keep them once you have them). 

But don’t despair! If you target long-tail keywords and implement best practices for SEO copywriting, you can start to see results (and an increase in incoming organic traffic) in a few months. 

On the other hand, you can get near-instantaneous results if you focus on PPC as part of your SEM strategy. You write some ad copy, start the engine on your ads, and get traffic and conversions in just a few hours.

That doesn’t mean you’ll see an instant ROI, though. You’ll need to test and tweak your ads consistently to get a positive ROI from PPC campaigns.

But there’s no doubt: PPC does start working much more quickly than traditional SEO.

SEO vs. SEM: The Financial Investment

SEO predominantly involves indirect costs. While you might not be paying for every click or view, you’re still shelling out for that traffic in terms of time and resources. You might hire experts to optimize your site or invest in link-building tools. Over time, these costs can add up. 

You’ll also need to consider the time you spend doing content creation, backlink outreach, and website optimization.

For SEO, the complexity of your website, the competition in your industry, and the region or market you’re targeting can all affect your expenses. 

For instance, aiming to rank for a keyword like “best digital marketing tools” will be far more competitive (and likely more expensive) than a more niche keyword like “best tools for bonsai tree care.”

PPC has direct costs attached. You pay per click, so depending on the competitiveness of your keywords, these costs can range from a few cents to several dollars per click.

Factors like the quality of your ads, the effectiveness of your landing pages, and the geographical regions you’re targeting can significantly influence PPC costs. If you’re advertising a luxury product in a high-income region, expect higher costs per click compared to advertising a common household product.

Setting a PPC budget will help you control spending, but you’ll need to continually monitor and adjust your campaigns to ensure they’re cost-effective. And if you stop spending on PPC ads, the faucet will turn off immediately, and your traffic will stop.

But cost shouldn’t be the only factor. It’s also about value. SEO can provide long-term, sustainable traffic at a (relatively) fixed cost. On the flip side, SEM can offer you immediate traffic, but costs can fluctuate based on competition and market dynamics. 

Balancing the two ensures immediate visibility and sustained long-term presence in search engines.

SEO vs. SEM: Attracting the Right Visitors

With SEO, the traffic is inherently targeted because users are actively searching for specific terms or questions your content addresses. If your site ranks well for relevant keywords, it means the visitors coming to your site are looking for the information or solutions you provide. 

This organic traffic can lead to excellent engagement and high conversions if you play your cards right.

SEM, especially through PPC campaigns, also allows for precise targeting. Advertisers have the ability to define their audience based on demographics, interests, behaviors, and more. By setting these parameters, the ads are displayed only to people who fit the profile you’ve created.

Traffic from PPC can potentially be highly targeted, but it’s crucial to continually refine and optimize your advertising campaign parameters to maintain relevance.

The goal is to draw in visitors who are genuinely interested in what you offer. Properly executed, both strategies can drive highly targeted traffic to your website.

SEO vs. SEM: Long-Term Traffic Potential

The entire goal of SEO is to get sustained organic traffic. Once a web page has ranked well for specific keywords, it can continue to attract a consistent flow of visitors without additional spending. 

However, maintaining your ranking requires ongoing optimization efforts, especially in competitive niches. Sudden drops in traffic can occur due to algorithm changes or increased competition, so you’ll need to keep a close eye on your website traffic over time. 

Use Semrush’s free website traffic checker to monitor your traffic over time, head those algorithm changes off at the pass, and maintain your rankings. 

Free Website Traffic Checker

PPC campaigns can deliver large volumes of traffic in short bursts. As long as you’re willing to pay for the clicks, the traffic keeps coming — but again, the moment the budget dries up or the campaign ends, this traffic source stops. 

While it’s possible to maintain consistent traffic through PPC, it requires a consistent budget and continuous campaign management.

In the long run, SEO offers more stable and sustained traffic, albeit with a slower start. PPC (as part of SEM) provides the advantage of immediate results, but its longevity relies on ongoing investment.

SEO and SEM: How to Pick the Best One for Your Goals

Understand the primary difference between SEO vs. SEM? Great. Next, I’ll help you figure out when and where you should use each.

When to Choose SEO

SEO is your best option if you’re operating on a tight budget or offering products that aren’t conducive to traditional marketing methods.

If your business model has narrow margins, like in dropshipping, the consistent costs of PPC might need to be revised. Additionally, if time is on your side and you don’t need instantaneous results, SEO is the logical choice.

Regardless of your chosen strategy, working on SEO as early as possible (preferably as soon as you launch your site) is highly beneficial. It’s a long game, but many SEO case studies show long-term results.

When to Choose SEM

Use SEM when you have a budget specifically allocated for paid marketing. It’s especially effective if you have a clear understanding of your target audience’s demographics, behaviors, and interests. 

If you’re selling a high-volume product where the costs of PPC will maintain your profit margins, SEM can be your go-to strategy for quicker visibility and conversions.

When to Choose Both

Generally, if your product is suitable and you have the budget, choosing both is the best strategy. SEO and SEM work together to ensure immediate and long-term online visibility.

SEM can enhance brand visibility, which in turn supports SEO efforts, and SEO-generated content can accrue backlinks from SEM promotions. When used in conjunction, these strategies can maximize your online presence and conversion potential.

Bring SEO and SEM Together

As you can tell by now, this isn’t really an SEO vs. SEM debate. Choosing between the two isn’t an either/or — it’s about finding the right balance for your goals.

Whether you’re crafting a long-term organic strategy or looking for paid results (or both!), Semrush provides all the tools SEOs need.

Claim your free 7-day trial today to get started!