SEO vs. SEM: What’s the Difference and Why Should You Care?

Joshua Hardwick
Head of Content @ Ahrefs (or, in plain English, I'm the guy responsible for ensuring that every blog post we publish is EPIC).
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    Search engines like Google have two types of search results: paid and organic.

    Paid results show up when companies pay Google for clicks. 

    Organic results are the ones that Google deems most relevant for the query.

    organic vs paid results

    Business owners can increase website traffic by appearing in organic and paid results using SEO and PPC.

    In this guide, we cover when and how to use SEO, PPC, or both for a more comprehensive search engine marketing (SEM) strategy.

    But first, let’s cover the basics.

    SEO (Search Engine Optimization) is the practice of optimizing content to be discovered through a search engine’s organic results.

    Google and other search engines look at hundreds of factors to decide which pages to rank for queries. Nobody knows what all of these factors are, but the most important ones are roughly divided into three buckets:

    On-page SEO

    On-page SEO is the practice of optimizing individual web pages.

    Examples of on-page tactics include:

    Off-page SEO

    Off-page SEO is anything done outside of a website to improve its rankings.

    Examples of off-page tactics include:

    Those marked with (*) are mainly important for local business SEO.

    Technical SEO

    Technical SEO involves making technical changes to help search engines crawl, index, and rank content more efficiently.

    Examples of technical optimizations include:

    PPC (Pay Per Click) is a form of advertising where businesses pay for website clicks from popular platforms like search engines.

    For example, clicking this ad in Google costs Apple money:

    1 apple ipad ad

    SEM (Search Engine Marketing) is a broad term that encompasses SEO and PPC.

     Not everyone agrees with this definition. Some see SEM as synonymous with PPC.

    Knowing what we now know about search engine marketing, it’s easy to jump to the conclusion that SEO is the way forward because organic traffic is free, consistent, and passive.

    This isn’t always the case.

    Sometimes SEO works best; other times PPC is the better option. And sometimes, it makes the most sense to use both marketing strategies at the same time.

    Below are four ways to use SEO, PPC, or both for maximum search engine visibility and traffic.

    1. Run ads for keywords that are too competitive
    2. Use PPC and SEO for ad-heavy keywords
    3. Use SEO for informational keywords
    4. Use SEO and PPC to monopolize the search results

    1. Run ads for keywords that are too competitive

    It can take years to rank for some keywords.

    For example, if you have a new supplement store and want to rank for “buy protein powder,” your chances of ranking in the short-to-medium term are slim.

    This is because you’re going up against established brands like Amazon, Walmart, and GNC.

    2 protein powder competition

    But this doesn’t mean you should abandon SEO and just run ads.

    Since ranking for competitive queries will likely be a long-play, there are a few benefits to using PPC while working to rank your pages.

    a) You can generate revenue immediately

    Paid traffic is instant. It can be turned on or off with the click of a button.

    Send that traffic to a relevant page optimized for conversions, and you can make sales in minutes.

    Just remember that revenue isn’t the same thing as profit.

    If you sell a product for $10, pay $1 per click, and convert at 20%, you’re turning every ad dollar spent into two.

    ad cost table

    But if your product costs $6 to make, you’re losing money.

    ad profit table

    There are two ways to fix this without increasing the price of your product:

    1. Increase your conversion rate
    2. Decrease your cost per click (CPC)

    Achieving both of these can take months, so be prepared to lose dollars while you tweak campaigns and pages to work for you.

    b) You can test and optimize for conversions

    Most ad platforms have conversion tracking features. They know that if publishers see a positive return on their ad spend, they’ll keep spending.

    Use this as an opportunity to gain insights on the average cost per conversion and run controlled tests to improve your conversion rate. As you start producing profit from your ads, scale-out to other platforms (e.g., Bing ads).

    c) You can get valuable keyword data

    The “Search terms” report in Google Ads shows conversion data for the keywords you’re bidding on.

    3 conversion rate google ads

    Use this to find high-converting keywords to target with SEO.

    For example, let’s say that you sell protein powder.

    Bidding on a popular keyword like “protein powder” might result in tons of clicks but low conversions. For a more specific query like “grass fed whey protein,” you might get fewer clicks but more conversions.

    So here’s what you can do:

    Export the search terms report from Google Ads, filter for profitable ones, then paste them into Ahrefs’ Keywords Explorer to pull their SEO metrics. Next, sort by Keyword Difficulty to find those that are probably easiest to rank for organically.

    4 keyword difficulty

    2. Use PPC and SEO for ad-heavy keywords

    Profitable keywords tend to attract lots of advertisers.

    Just look at the results for “car insurance”:

    5 car insurance ads

    Google shows four paid ads at the top, and that leads to fewer clicks on organic results as they get pushed down the page.

    How many fewer clicks?

    For that keyword, almost 40% go to paid results.

    6 paid results 1

    PPC, then, is a great way to get traffic from this keyword, but what about SEO?

    If we look at estimated organic traffic to the current top-ranking page for this keyword, we see that it gets an estimated 64,000 monthly organic visits.

    7 car insurance organic traffic

    Bottom line: Invest in SEO and PPC to get maximum traffic from ad-heavy keywords.

    3. Use SEO for informational keywords

    Most Google searches are informational.

    That means people are looking to learn, not buy.

    For example, take a query “how to make a protein shake,” which gets 2,100 searches a month.

    8 keyword search volume

    It’s unlikely that anyone searching for this is in the market for protein powder. Most are probably looking to learn how to make a tasty shake using powder they’ve already bought.

    That explains why no supplement companies bid on this keyword. It doesn’t make financial sense, even with a low average CPC.

    9 organic results

    Looking at the search results, however, we see one supplements company ranking organically at the bottom of the first page.

    10 how to make a protein shake organic

    It’s clear from the title of the post that this was no accident; they’ve made an effort to rank for this keyword.

    The question is, why are they willing to put effort into ranking organically, but aren’t willing to pay for traffic to that page?

    The answer comes down to cost vs. reward.

    The top-ranking page for that keyword gets around 9,000 monthly organic visits. The estimated PPC value of that traffic is $16,400.

    11 ppc value

    Given the low Keyword Difficulty score for this query, the dollar-equivalent of the time and effort required to rank organically would almost certainly be less in comparison.
    kd score how to make a protein shake 1

    4. Use SEO and PPC to monopolize the search results

    It’s not just ads that push down the organic search results.

    Google now shows SERP features like featured snippets, “People also Ask” boxes and video carousels for some queries.

    14 serp features

    These can be annoying when your goal is to rank higher, but remember that it’s possible to appear in many SERP features.

    Look at the query, “how to rank youtube videos.” We appear in the video snippet, video carousel, and near the top of the “blue link” organic rankings.

    13 ahrefs rankings

    This is true of many SEO-related keywords because we’re committed to providing the best resources for learning SEO. We also optimize our videos to rank in Google.

    Some brands choose to monopolize the search results even further by running ads for keywords they already rank for.

    For example, one website is running ads for “how to start a blog” despite already ranking organically and owning the featured snippet.

    12 snippet organic ad

    Final thoughts

    Search Engine Marketing (SEM) isn’t a never-ending wrestling match between SEO and PPC. Knowing when and where to use each tactic to achieve the desired results is the game.

    Sometimes SEO is the answer, sometimes PPC, and sometimes both.

    Looking to learn more about SEO? Check out our SEO training course for beginners.

    Looking to learn more about the pros and cons of each? Read our guide to SEO vs. PPC.

    • Linking websites 50
    • Tweets 78
    Data from Content Explorer