GEO, AEO, LLMO: What's the Difference, and Which One to Choose in 2026?

The AI search acronym decoder

The vocabulary of AI search has not settled: every SEO agency pushes its own acronym, and the French market counts at least six. Here is what each one actually covers:

1. GEO (Generative Engine Optimization): the term formalized by an academic study from Princeton and Georgia Tech in 2023. GEO optimizes content so it gets cited in the answers generated by AI engines. It is the dominant acronym in France.
2. AEO (Answer Engine Optimization): emerging around 2019-2020 with featured snippets, AEO structures each page to answer a question directly in an answer-first format. Google's AI Overviews are its direct heir.
3. LLMO (Large Language Model Optimization): the technical layer targeting what language models know: entity graph, brand consistency across the web, press mentions, allowing AI crawlers (GPTBot, ClaudeBot) in robots.txt.
4. GSO (Generative Search Optimization): a terminology variant pushed by some French agencies, with a scope equivalent to GEO.
5. AISO (AI Search Optimization) and AI SEO: the generic formulations; "SEO IA" remains what French executives actually type into Google.
6. Agentic SEO: the next frontier, floated at Google in 2026: optimizing for AI agents that act (book, buy, compare) and no longer just for engines that answer.

80-90% rebranded SEO: the common foundation

The consensus among practitioners, from Rand Fishkin to John Mueller, is unambiguous: the vast majority of optimizations sold under the GEO or LLMO label are classic SEO. Generative engines rely on the traditional web's indexes: ChatGPT Search queries the Bing ecosystem, Gemini leans on Google's index and its Knowledge Graph, Perplexity crawls the open web. A technically sound site — fast, well interlinked and rich in expert content — therefore feeds both channels at once.

The data backs this up: according to Ahrefs, 96% of citations in AI Overviews come from sources with strong E-E-A-T — that is, sites that already tick every box of organic search: demonstrated expertise, identified authors, built authority. GEO does not replace SEO; it rewards it.

The 10-20% that genuinely change the game

Then there is the specific part, and it is measurable. Four signals stand out from the citation studies conducted in 2025-2026:

• The answer-first format pays off: FAQ pages are cited 3.2 times more than narrative pages, and structured tables 2.5 times more (CMU/GenOptima study of 50,000 citations). A two-sentence answer at the top of the page is the format models extract most readily.
• Editorial freshness dominates: 76% of the pages most cited by ChatGPT were updated less than 30 days ago (ziptie.dev). Dated, maintained content beats brilliant but frozen content.
• Google rankings are no longer enough: 88% of URLs cited by LLMs do not appear in Google's top 10 (Brandlight). The citation layer and the ranking layer are two separate competitions.
• Entity density drives citability: models reason in entities and explicit relationships. Content where every claim links a subject, a predicate and a verifiable object gives generative engines material to extract. That is precisely what our Contextual Density methodology measures.

The llms.txt case: emerging standard or myth?

Honesty requires it: the llms.txt file divides opinion. No independent study has shown to date that it increases citations, and some practitioners file it among the myths of GEO. Our position is pragmatic: implementation costs ten minutes, the file serves as a readable editorial map for AI crawlers, and it cannot hurt. We therefore deploy it systematically, without attributing magical powers to it. The real levers remain citable content and entity authority.

What this changes for your 2026 budget

The French market is tipping: according to the Semji study of 379 professionals, 63% of French marketing teams plan intensive GEO investment in 2026. Meanwhile, the share of web traffic actually coming from LLMs remains modest, around 2% of total traffic, but it is ultra-qualified traffic: Bain & Company measures +35% organic clicks and +91% paid clicks for brands cited in an AI answer.

The budget conclusion writes itself: do not create a separate "GEO" line that cannibalizes your SEO. Extend your organic search program with a generative layer: answer-first formats, monthly refreshes, an entity graph, and citation tracking that measures your generative share of voice engine by engine. That is the architecture of our AI SEO agency offering, and it applies language by language for international brands, as in international SEO.

How to monitor your AI visibility: tools and method

GEO without measurement is an act of faith. Three families of tools took shape in 2025-2026 to turn citations into a KPI:

• Specialized citation trackers: Otterly, Profound or Brandlight query ChatGPT, Perplexity, Gemini and Copilot daily on your target queries, count mentions of your brand and your competitors', and report a dated generative share of voice.
• The legacy SEO suites: Semrush and Ahrefs have added AI Overviews and AI citation tracking to their rank trackers, handy for unifying rankings + citations reporting in a single dashboard.
• The manual method: a panel of 20 strategic queries, asked monthly across the four engines from a neutral session, capturing the cited sources. Artisanal but free, and sufficient for an SMB getting started.

One methodological warning: generative answers are unstable. Two users asking the same question can receive different citations, whereas a Google ranking was roughly reproducible. Meaningful tracking is therefore statistical: a citation frequency across a volume of runs, not a single position. It is a culture change for teams used to classic rank tracking.

Where to start: the first-30-days checklist

1. Week 1: the baseline. Measure where you stand: is your brand cited on your 20 key queries? Are your AI crawlers (GPTBot, OAI-SearchBot, ClaudeBot, PerplexityBot) allowed in robots.txt? Is your Bing indexing clean (IndexNow, Bing Webmaster Tools)? ChatGPT Search relies on that ecosystem.
2. Week 2: the answer-first format. Rewrite the opening of your 10 most strategic pages: a direct two-to-three-sentence answer, then the development. Add a FAQPage-marked-up FAQ to each: FAQ pages are cited 3.2 times more.
3. Week 3: the entities. Check your brand's consistency across the web: same name, description and contact details everywhere, LinkedIn profiles and directories aligned, identified authors with worksFor markup. That is the raw material of the entity graph the models memorize.
4. Week 4: the freshness loop. Set up a dated monthly update rhythm on your key pages: 76% of the most-cited pages are less than 30 days old. Then rerun the measurement and compare against the baseline.

This four-week plan requires no media budget: it is editorial and technical discipline. The difference is made through consistency, exactly as it has been in organic search for twenty years.

FAQ: the questions everyone asks

Is SEO dead because of AI?

No: it has become the price of admission. Generative engines primarily cite sites that already perform in organic search. What is dying is purely positional SEO that ignores the citation layer.

How do I know if my site is cited by AI engines?

By systematically querying ChatGPT, Perplexity, Gemini and Copilot on a panel of strategic queries, every month, and counting citations of your brand against your competitors. Specialized tools (Otterly, Profound, Brandlight) industrialize that counting.

How long before you see GEO results?

The first citation effects appear within 4 to 12 weeks on lightly contested queries, because AI engines refresh their sources faster than Google recalculates its rankings. Entity authority, on the other hand, is built over 6 to 12 months.

Should I stop my current SEO efforts to do GEO?

Absolutely not: 80-90% of the work is shared. Stopping SEO to fund GEO amounts to sawing off the branch that carries your future citations.

Is GEO relevant in B2B?

Particularly so: Copilot is embedded in Microsoft 365 and B2B decision-makers use ChatGPT heavily during the pre-selection phase. Being cited at that stage means making the shortlist before the first call even happens.

Written by Éric St-Cyr, founder of ProStar SEO and Agence SEO Paris — LinkedIn profile.