SEO vs AEO vs GEO in 2026: The Differences That Matter (and the One Thing That Doesn't Change)

SEO, AEO and GEO differ in which engine you are trying to win and how you measure it. They share one rule that does not change: an engine can only cite a page it can crawl, index and trust. Google said in July 2026 that for its own AI features, all of it is still SEO.

This guide was first published in May 2026 and rewritten on October 16, 2026 with Google's official guidance and our own measurements. Value Add VC's pages drew 1.91 million impressions in Google's AI Overviews and AI Mode from mid-July to mid-October 2026, documented in our AI search traffic case study, so the differences below come from what we see, not from vendor decks.

SEO vs AEO vs GEO: the short answer

In SEO vs AEO vs GEO, SEO earns ranked links, AEO earns the direct answer to a question, and GEO earns citations inside AI-written responses. For Google, the three are one job: its AI features run on core Search ranking. For ChatGPT, Perplexity and Claude, GEO adds crawler access and citation tracking.

Sources: Google AI optimization guide (July 10, 2026); OpenAI crawler docs; Perplexity crawler docs; Aggarwal et al., arXiv 2311.09735. The SEO and AEO origin rows and the summary wording are Value Add VC's.

What is AEO, and what is GEO?

AEO, answer engine optimization, is an industry label for making a page the single answer an engine gives: a featured snippet, a voice reply, an answer box. It asks one question of a page: does it state the answer plainly, near the top, in a sentence that still makes sense when lifted out?

GEO, generative engine optimization, has a paper trail. Pranjal Aggarwal and five co-authors formalized it in "GEO: Generative Engine Optimization," posted to arXiv on November 16, 2023. They built GEO-bench, a benchmark of user queries across domains, and reported that their methods "can boost visibility by up to 40% in generative engine responses," with results that varied by domain. That is a lab result on a benchmark, not a measured gain on live Google traffic.

Google's answer to both labels came in its guide to generative AI features: "From Google Search's perspective, optimizing for generative AI search is optimizing for the search experience, and thus still SEO." We break down the rest of that guide in Google's AI optimization guide, explained.

What doesn't change between SEO, AEO and GEO?

Access and substance. Google says a page must be "indexed and eligible to be shown in Google Search with a snippet" to appear in AI Overviews or AI Mode, and that unique, non-commodity content will likely matter "more than any of the other suggestions in this guide." Other engines have the same dependency on their own crawlers: OpenAI says sites opted out of OAI-SearchBot "will not be shown in ChatGPT search answers."

We learned the access rule the hard way. A site-wide noindex header was live on Value Add VC for about 28 hours on September 16-17, 2026, and daily search impressions fell about 55% at the low point, per the results file in our open-source playbook. No amount of AEO formatting matters for a page an engine cannot index. Speed belongs in the same bucket: our real-user mobile LCP is 1.8 seconds and INP 94 ms, inside the 2.5-second and 200 ms "good" lines on web.dev.

Both metrics sit well inside Google's thresholds; desktop LCP is 1.0s and CLS is 0 on mobile.

Where do SEO, AEO and GEO actually differ?

1. Which crawlers you let in

SEO deals with Googlebot and Bingbot. GEO adds a set of AI agents with separate jobs. OpenAI runs OAI-SearchBot for ChatGPT search, GPTBot for model training and ChatGPT-User for live user requests. Perplexity runs PerplexityBot for search and Perplexity-User for live requests. Anthropic's help center lists ClaudeBot for training, Claude-SearchBot for search and Claude-User for user requests. Because the vendors separate them, a site can allow search crawlers and block training crawlers, a choice SEO never had to make.

2. What success looks like

SEO counts clicks. GEO has to count citations, and many citations never become clicks. Value Add VC's weekday AI impressions grew from about 10,000 a day in July 2026 to about 40,000 in October, while AI-assistant visits fell from 744 on September 17-30 to 537 on October 1-14. Our read is that more AI answers cite us without the reader needing to click.

3. The shape of the query

AI engines search on the user's behalf. Google calls it query fan-out, "a set of concurrent, related queries generated by the model." In our Search Console, machine-shaped queries drew 301K blog impressions at a 0.01% CTR in the 28 days to September 21, 2026, against 360K human-shaped impressions at 0.95%. SEO reporting that lumps those together overstates human reach.

4. How you measure it

SEO has one dashboard. GEO needs four views: Search Console's Generative AI report, GA4 referrals, server logs and a prompt panel. Our guide to tracking AEO and GEO walks through each with free tools.

Do schema markup and llms.txt matter for AEO?

For Google, no special version of either. Google's guide says "there's no special schema.org markup you need to add" for generative AI search, though structured data still helps with rich results. It says Google Search does not use llms.txt and that a file will "neither harm nor help" there. It also says you do not need to chunk content or rewrite it for AI.

Outside Google, llms.txt is a convention some services use; Perplexity's own developer docs point AI agents to an llms.txt index. Value Add VC publishes one and keeps standard Article and FAQ schema, but we do not credit either for our Google AI impressions. Our llms.txt explainer covers when it is worth keeping.

How do SEO, AEO and GEO work together on one page?

On a single page the three disciplines stack rather than compete. Here is the template every Value Add VC explainer follows, with the layer each element serves. It is our house standard, not a Google requirement.

Source: Value Add VC editorial standard, October 2026. The "mostly serves" column is our judgment.

Our read is that the fact-sentence rule matters most for AI citations, because an AI answer quotes a sentence, not a page. "It raised more" after a paragraph break is useless out of context; "Anthropic's annualized revenue reached a stated figure in a named month, per a linked source" can be lifted whole. None of this needs special markup, and all of it helps human readers too, which is the test Google's guide sets: "Is this content that my visitors would find satisfying?"

Which should a startup prioritize?

Our read: start with SEO hygiene, because it is a precondition for the other two on Google, and on our site Google sends most of the traffic: ordinary Google Search delivered 60.9K clicks in the three months to mid-October 2026, while all AI assistants combined sent 537 visits in two weeks. A startup with ten hours a month should spend most of them on indexable, answer-first pages about the questions its buyers ask.

Then add the GEO layer where it is cheap: allow the AI search crawlers, publish one first-hand data point competitors cannot copy, and run a 25-prompt citation check monthly. Skip agencies that sell AEO or GEO as a separate discipline with secret tactics; Google's guide tells site owners to review such advice against its guidance on evaluating third-party SEO advice. Our longer case for organic search as a startup channel is in why SEO is still the best long-term growth investment.

What gets a page cited, in our data?

The pages AI assistants send readers to on our site are data and money explainers: the AI spending tracker, OpenAI revenue, OpenAI API pricing, Anthropic profitability and CoreWeave's backlog. Each one answers a money question with a dated, sourced figure in its opening sentence. That is the same thing good SEO, AEO and GEO each ask for, and it fits what Google calls non-commodity content.

Where we could be wrong

Google has an interest in telling publishers that nothing new is required, and its guide covers only Google. ChatGPT, Perplexity and Claude do not publish ranking guidance of the same depth, so GEO tactics for them are still mostly tested by trial. Our own data is one finance-heavy site over a few months; a retailer or local business could see a different mix of engines and pages. And the GEO paper's 40% figure shows that wording changes can move citations in a benchmark, which is a reason to keep testing rather than to assume formatting never matters.

What should you do in 2026?

1. Fix access first: indexing, snippet eligibility, robots.txt and CDN rules for the search crawlers you want.
2. Decide on training crawlers separately (GPTBot, ClaudeBot, Google-Extended) from search crawlers.
3. Put the answer and its date in the opening sentence of the pages you want cited.
4. Add first-hand data no one else has; it is what makes a page non-commodity.
5. Measure four ways and read impressions and referrals together.
6. Skip the hacks Google names: chunking, AI-only rewrites, fake mentions and special AI files.

The scripts we use for indexing checks and query splits are in our AI SEO playbook, and you can check any page's basics with the free SEO score checker.