Updated
Updated What changed on
- Added the range of published prevalence estimates rather than a single vendor figure.
- Added Ahrefs' March 2026 study on how AI Overview citations relate to organic rankings.
AI Overviews vs AI Mode: what each one actually does.
The 30-second verdict
Both are Gemini 3-powered surfaces inside Google Search. AI Overviews appear automatically above organic results on roughly 47% of UK desktop and 53% of UK mobile queries. AI Mode is a separate, opt-in conversational experience using stronger query fan-out (decomposing one prompt into 5-7 sub-queries). Optimise for AI Overviews first because of reach; the work overlaps about 90% with AI Mode so the marginal cost of covering both is low. Both controlled by Google-Extended bot access.
What is measured about AI Overviews
of Google searches trigger an AI Overview, depending entirely on whose panel you read.
How it was measured: Pew measured 18% on real-user browsing data. Ahrefs measured 48% of its keyword set in March 2026. Similarweb reported 43%, up from 15% a year earlier, via TechCrunch on 27 July 2026. The panels sample different query mixes, so the spread is a methodology artefact. Anyone quoting a single figure as the number is overstating what is known.
Sources disagree on this one. The range is the honest answer.
of pages cited in Google AI Overviews also rank in the top 10 for that query.
How it was measured: 863,000 keyword SERPs and 4 million AI Overview URLs. Ahrefs measures the top 10 as blocks, counting ads, featured snippets and video packs as separate blocks.
was the same measurement in July 2025, so the overlap between ranking and being cited has roughly halved in eight months.
How it was measured: 1.9 million citations from 1 million AI Overviews. Ahrefs notes it improved its parsing between this study and the 2026 update, so part of the change may be measurement rather than behaviour.
Side-by-side comparison
 AI Overviews |  AI Mode | |
|---|---|---|
| Position in Google Search | Above traditional organic results, automatic | Separate opt-in surface (tab / button) |
| Underlying model (since 27 Jan 2026) | Gemini 3 | Gemini 3 |
| UK trigger rate | 47% desktop, 53% mobile, 71% informational queries (Semrush 2026) | Voluntary opt-in - user has to choose AI Mode |
| UK launch | Live since 2024 | 28 July 2025 |
| Query handling | Light query fan-out, primarily synthesises top-ranked sources | Heavy query fan-out (5-7 sub-queries per prompt) |
| Output format | Concise paragraph + linked citations | Conversational, longer, follow-up enabled |
| Agentic actions | None | Yes - UK has restaurant bookings via OpenTable, TheFork, SevenRooms since April 2026 |
| Rank correlation (Ahrefs) | Spearman 0.65; top-3 pages ~30x more likely to be cited per-page | Similar correlation; sub-question coverage on one URL gains additional citation share |
| Bot control | Google-Extended | Google-Extended |
| Optimisation priority for UK B2B | 1st (reach) | 2nd (depth + agentic future) |
Where they overlap (the shared 90%)
Both use RAG over Google's search index. Both are gated by Google-Extended bot access. Both reward strong ranking (top-3 wins per-page), content depth on the query, named-author credibility signals, and clean extractable structure. Schema (Article + FAQPage + HowTo where relevant) is hygiene that quality sites carry anyway - ship it but expect ranking and depth to do the citation work (per Ahrefs' May 2026 controlled test).
Where they differ (the 10%)
AI Mode's heavy query fan-out is the practical difference. A page that bundles parent topic + related sub-questions on one URL wins multiple citation rounds in AI Mode for one user prompt. AI Overviews uses a lighter fan-out and tends to cite cleaner single-topic sources.
The other difference is agentic action. AI Mode UK now does actual bookings; AI Overviews does not. For travel, hospitality, restaurants and any sector where agentic flows matter, AI Mode is the surface to prepare for. For information-only sectors (consultancy, professional services, B2B technical), AI Overviews reach matters more in the short term.
Practical pick order
For 9 out of 10 UK brands the order is: AI Overviews first (reach), AI Mode second (depth + future agentic surface). The work is largely shared so cover both unless you genuinely have nothing to expose to an agent.
What 730,000 Ahrefs response pairs revealed
Ahrefs' December 2025 study ran the same 365,000 queries through both surfaces and compared the responses head-to-head. Five findings that matter for optimisation:
- URL overlap was only 14% - of the sources cited by AI Overviews and AI Mode for the same query, fewer than one in seven matched. Treating them as one surface to optimise for misses 86% of the citation opportunity.
- Word overlap was just 16% - the two surfaces phrase answers very differently from the same source material. Different sentences get extracted, so writing for one specific extraction pattern under-serves the other.
- Responses were 90% semantically similar - the underlying answer is largely the same; presentation, citation set and length differ sharply.
- AI Mode responses are 4x longer and cite 3x more entities (3.3 vs 1.1 brands/people per answer) - which means AI Mode is the bigger surface for brand-mention visibility, not just citation links.
- 59% of AI Overviews contain no brands or entities at all - AI Overviews often answer with pure information; entity inclusion is much more common in AI Mode. For brand-led SEO the AI Mode surface is the higher-yield work.
The practical read: optimise for AIO first because of reach, but treat AI Mode separately for brand mention because the AI Mode answer is where your brand actually has a 3x better chance of being named.
More on AIO vs AI Mode.
Is AI Mode replacing AI Overviews?
Not for now. AI Overviews stay above traditional search results. AI Mode is a separate, opt-in conversational experience. Both are Gemini 3-powered (since 27 January 2026) and share the same underlying retrieval mechanism, but they live as parallel surfaces inside Google Search.
Which should I optimise for first?
AI Overviews. They appear automatically on 47% of UK desktop and 53% of UK mobile queries (Semrush 2026 data), and approximately 71% of UK informational queries. AI Mode requires opt-in user activation. The optimisation work overlaps about 90% so the marginal cost of also serving AI Mode is low.
Do they use the same retrieval mechanism?
Both use RAG (retrieval-augmented generation) over Google's index. AI Mode additionally uses query fan-out - decomposing one user prompt into 5-7 sub-queries. AI Overviews use a lighter version of fan-out. The implication: content that bundles topic + related sub-questions on one URL wins more citation share in AI Mode than in AI Overviews.
Does Google-Extended control both?
Yes. Allowing or blocking Google-Extended affects citation eligibility on both AI Overviews and AI Mode. Blocking it removes you from both surfaces without affecting traditional organic ranking.
When did AI Mode launch in the UK?
Google opened AI Mode to UK users on 28 July 2025. AI Mode UK is now agentic (restaurant bookings via OpenTable etc since April 2026). AI Overviews has been live in the UK longer.
Jason Burns
Independent UK SEO, GEO and AI consultant. 17 years in search. Portfolio includes 3M, BlackRock, Unilever and E.ON. Owner of SEO Moves Ltd since 2014.
More about Jason →See your pages against both surfaces together.
Send three priority queries. I run each through AI Overviews and AI Mode separately and send back which surface cites you on which query and where the gap is.
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