GEO vs SEO vs AEO: what's the difference?

SEO (search engine optimization) is about ranking pages in search results and earning clicks. AEO (answer engine optimization) and GEO (generative engine optimization) are about being mentioned, recommended or cited when an AI system writes the answer itself, in products like ChatGPT, Google AI Overviews, Google AI Mode, Gemini, Perplexity or Claude.

GEO was named in a research paper by Aggarwal and colleagues, first posted in November 2023 and published at KDD 2024.^[3] AEO is a label many marketers and vendors use; HubSpot, for example, sells its AI visibility product under the name AEO.^[9] In practice the two describe the same work. Our guide to generative engine optimization covers GEO on its own.

Google's own framing is worth knowing before you hire anyone: from Google Search's perspective, optimizing for generative AI search is optimizing for search, and so it is still SEO. Google also suggests checking third-party AEO or GEO advice against its documentation.^[1]

The table below compares the three on the points that change day-to-day work. AEO and GEO share a column because the practical differences between them are small.

They overlap in almost everything that makes a site findable and trustworthy. Most AI answer engines retrieve pages from a search index before writing, so the basics of SEO are the entry ticket to GEO.

• Indexing. Google says a page must be indexed and eligible to show a snippet to be a supporting link in AI Overviews or AI Mode, and that there are no extra requirements beyond that.^[2]
• Retrieval. Google describes its AI features as grounded in the Search index, often using query fan-out to run several related searches.^[1][2] OpenAI says it may also get URLs from third-party search providers.^[5]
• Useful, original content. Google recommends unique, first-hand content over generic summaries for both classic and AI results.^[1]
• Reputation. Reviews, directories, press and expert mentions shape both rankings and what an AI says about you.
• Structured business data. Google points local businesses and stores to Business Profile and Merchant Center data, which feed both AI responses and regular results.^[1]

Five things change when you add GEO to an SEO program. None of them requires a separate website or a new kind of markup; they change what you check and how you report.

1. You track mentions, not just positions. An answer may name three brands and link to none of them. A furniture store in Chicago or a payroll app in Singapore needs to know whether it is in that list, which is a different measurement from rank.
2. You ask unbranded questions. "Best accounting software for freelancers in Spain" tells you more than "is our brand good?", because AI nearly always mentions you when asked about you by name.
3. You manage more crawlers. Each engine has its own search bot, controlled separately from training bots. OpenAI, for instance, treats its search crawler and training crawler as independent settings.^[4] Check yours with the AI crawler checker.
4. You care about who cites you. The pages an engine reads for your category, such as review sites, comparison articles and forums, become part of the work. The GEO paper found that adding statistics, quotations and source citations to content raised its visibility, while keyword stuffing did little.^[3]
5. You measure with samples and ranges. Research by SparkToro and Gumshoe found less than a 1 in 100 chance that two AI answers to the same question list the same brands, and recommended measuring visibility as a percentage across many runs.^[6] See why AI answers change.

No. AI answers sit on top of search indexes, and the engines' own guidance tells site owners to keep doing SEO. Google says there are no special optimizations needed for AI Overviews or AI Mode beyond being indexed and snippet-eligible.^[2] What has changed is that ranking is no longer the whole story: a page can rank well and still not be the brand an AI recommends.

The measurement tools reflect this. Google introduced Search generative AI performance reports in Search Console in June 2026,^[8] and Bing Webmaster Tools added an AI Performance report in February 2026 that counts citations in Microsoft Copilot and Bing's AI summaries.^[7] Both sit alongside, not instead of, the classic search reports.

They are more names for the same idea. LLMO stands for large language model optimization, AI SEO is a plain-language catch-all, and AIO is sometimes used for AI optimization or for Google's AI Overviews, depending on who is writing. The vocabulary differs by country and by vendor, so judge advice on what it tells you to do, not on the acronym it uses.

Treat GEO as an extension of your SEO program with its own measurement, not as a separate department. A small marketing team or an agency can run it with this checklist.

• Keep: technical SEO, indexing, page speed, internal links and helpful content. These remain the base for both.
• Add to audits: robots.txt and CDN rules for each AI search crawler, plus a check that key pages answer their main question in the first paragraph.
• Add to research: the unbranded questions buyers ask AI in each market and language you sell in, and which sources engines cite for them.
• Add to reporting: AI share of voice against named competitors, per engine, with sample sizes and ranges.
• Drop: keyword stuffing, AI-only page versions and any tactic sold with a guarantee.