SEO vs AI search (GEO): what's the difference?
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SEO gets you ranked on Google. GEO (Generative Engine Optimization) gets you cited by AI: ChatGPT, Perplexity, Google’s AI Overviews, Gemini. They overlap heavily, but the moment people started asking AI directly instead of clicking blue links, “rank #1” stopped being the whole game. Being the answer the AI quotes is the new one.
The difference in one sentence
SEO optimizes to be found in a list of links. GEO optimizes to be quoted in a generated answer. On a classic search you get ten blue links and the user picks one, and ranking is everything. In an AI answer the engine reads a handful of sources, synthesizes one reply, and names a few of them. If you’re not one of the sources it reads, you don’t exist in that answer, even if you’d have ranked first in the old list.
What they share
Most of the foundation is the same, which is why GEO isn’t a replacement for SEO:
- Crawlability. If a bot can’t read your pages, you can’t be ranked or cited. A stray
Disallow: /ornoindexsinks both. - Real, original content. Thin, copied, or auto-spun pages lose in both worlds.
- Structured data. Telling machines exactly what a page is helps Google rank it and helps AI quote it.
- Authority and trust. A clear identity, real authorship, and a reputation across the web matter to both.
So good SEO is the floor. GEO is the layer you add on top.
What’s actually different for GEO
A few things matter for AI citation that classic SEO never asked for:
- Let the AI citation bots in. ChatGPT, Perplexity, and AI Overviews crawl with their own agents:
OAI-SearchBot,PerplexityBot,Google-Extended. Plenty of sites block these by accident (or confuse them with the training bots like GPTBot, which is a separate choice). If the citation bots can’t read you, you can’t be cited. Full stop. - An
llms.txtfile. An emerging standard: a short markdown map of your most important pages, written for LLMs to ingest cleanly. Think of it as a sitemap for AI. - Quotable structure. Article schema, plus clear question/answer and step-by-step blocks written into the page, hand the engine content in the format it reproduces. Google dropped FAQ and HowTo rich results, so put the Q&A in the HTML, not just the markup.
- Question-style headings. AI prompts are questions. A heading phrased the way people ask (“How is junk silver priced?”) matches the prompt and gets pulled into the answer; a clever-but-vague heading doesn’t.
- Off-site presence. AI weighs mentions across the web: reviews, Reddit and forum threads, consistent name/address/phone. The real test isn’t a rank checker; it’s whether ChatGPT or Perplexity actually recommends you when asked.
Why it matters now
AI Overviews and AI search answer more questions without a click every month. When the answer appears at the top, fewer people scroll to the links beneath it, so being cited in the answer can be worth more than ranking first below it. The traffic doesn’t just move down the page; for some queries it never reaches the page at all. If your category is one where people increasingly ask an AI instead of searching, GEO isn’t optional anymore.
The honest version
You don’t pick one. GEO is built on top of SEO: secure, crawlable, well-structured, genuinely useful. Do the SEO basics first, then add the GEO layer: let the AI bots in, ship an llms.txt, mark up your content, phrase headings as questions. Skipping the foundation to chase the AI layer is like decorating a house with no walls.
Check both with GreenLight
GreenLight’s SEO check covers the foundation: titles, a single H1, a sitemap, thin content, canonicals. Its AI Search (GEO) check covers the layer on top: llms.txt, AI-bot access, structured data, question-style headings, and interlinked content. Point it at your site and it tells you, in plain language, exactly where you stand on both, and the exact fix for each gap.