Google AI Mode and AI Overviews Cite Different Sources — 67 Domains Apart
Machine Relations Index data on 500 top-cited domains shows Google AI Mode and AI Overviews diverge by 67 sources, and TechRadar — rank 7 overall — is cited by neither.
Search and brand teams checking AI visibility on a single Google surface are checking half the picture, even within Google. Machine Relations Index data covering the 500 most-cited domains across six answer engines shows Google AI Mode and Google AI Overviews — both built on the same Gemini foundation — diverge on 95 of those domains. TechRadar, the seventh most-cited domain in the entire 23,280-domain index, does not appear in either Google surface's citations during the measurement window, despite being cited by ChatGPT, Claude, Gemini and Perplexity.
Key takeaways
- Across the top 500 cited domains, Google AI Mode reaches 444 (88.8%) and Google AI Overviews reaches 377 (75.4%) — a 67-domain gap between two products from the same company.
- 81 of the top 500 domains are cited by AI Mode but not AI Overviews; 14 are cited by AI Overviews but not AI Mode; 42 are cited by neither Google surface at all.
- TechRadar.com (rank 7, confidence grade A, cited in 460 of 16,475 observed runs) is cited by four of six engines and by neither Google surface.
- Perplexity has the widest head overlap of the six engines (490 of 500, 98.0%); ChatGPT has the narrowest (361 of 500, 72.2%).
- The finding is a per-engine citation pattern, not a ranking signal or a causal claim about why any one domain is or is not cited by either surface.
What Machine Relations measured
The Machine Relations Index tracks 23,280 cited source domains across 15,782 to 16,475 answer runs (the run count varies by cut) over a 130-day window ending 2026-09-23, split across six engines: ChatGPT, Claude, Gemini, Google AI Mode, Google AI Overviews and Perplexity. Each of the top 500 ranked domains carries an engine_breadth field recording which of the six engines cited it at least once in the window — not a rate, a presence flag. That field is what this piece reads engine by engine (Machine Relations Index, release generated 2026-09-23, window 2026-05-10 to 2026-09-23).
Reading engine breadth across the top 500 domains gives a head-overlap ranking: how much of the most-cited supply each engine's answers actually touch.
| Engine | Domains reached (of top 500) | Share |
|---|---|---|
| Perplexity | 490 | 98.0% |
| Claude | 463 | 92.6% |
| Gemini | 452 | 90.4% |
| Google AI Mode | 444 | 88.8% |
| Google AI Overviews | 377 | 75.4% |
| ChatGPT | 361 | 72.2% |
Perplexity and Claude sit within a few points of universal head coverage. ChatGPT, the most consumer-recognized name on the list, has the narrowest reach of the six — a fact that matters for any brand team whose AI-visibility check is a single ChatGPT prompt.
Two Google surfaces, two different citation pools
The gap that carries the most operational weight is inside Google. AI Mode and AI Overviews are commonly treated as one product with two skins: both run on Google's query fan-out technique and a custom Gemini build, both surface inside Google Search, and Google itself reports both operating at billions-of-users scale — AI Overviews alone reaches roughly 2.5 billion monthly users (nadiamohamed.me, citing Google I/O 2026). But the products differ in how a user reaches them — AI Overviews appear automatically above organic results; AI Mode is a distinct tab a user opens for multi-turn, conversational search — and the Index data shows the citation pools differ too, not just the interface.
- 81 of the top 500 domains appear in AI Mode's citations but not AI Overviews': PCMag, Capterra, GlobeNewswire, Fortune and Fool.com among them.
- 14 of the top 500 appear in AI Overviews' citations but not AI Mode's: Mayo Clinic, Kiplinger and OWASP among them.
- 363 domains are cited by both.
- 42 domains in the top 500 are cited by neither Google surface — reachable by other engines, invisible to both Google products in this window.
A brand tracked only through AI Overviews and a brand tracked only through AI Mode are reading two different citation graphs, even though both graphs are labeled "Google."
The TechRadar case
TechRadar.com is the seventh most-cited domain in the entire 23,280-domain index, at confidence grade A: cited in 460 of 16,475 observed runs, on 101 of 130 observed days. It is cited by ChatGPT, Claude, Gemini and Perplexity — four of the six measured engines. Neither Google AI Mode nor Google AI Overviews cited it during the window.
That is not evidence TechRadar is losing visibility broadly; the domain is doing well by every other engine's measure. It is evidence that a search team validating AI citation performance by checking only Google's AI surfaces would conclude TechRadar has no AI presence at all, when the opposite is true everywhere except Google.
The same asymmetry runs the other way. Mayo Clinic and Kiplinger show up in AI Overviews' top-500 citations but not AI Mode's — sources a team checking only AI Mode would miss entirely.
Why the two surfaces might diverge
The Index data records presence, not cause, so this is a bounded, sourced note rather than a claim about Google's ranking mechanics. Public documentation on Google's crawler controls describes Google-Extended as the token governing whether a site opts into Gemini's model-training and grounding uses, distinct from the Googlebot token that governs standard Search inclusion — meaning a site's robots.txt posture can, in principle, affect one Google AI surface's access to a page without affecting the other or classic Search (capconvert.com). Whether crawler-access differences, live-retrieval differences between a passive summary and an active multi-turn session, or query-mix differences between the two surfaces best explain the 67-domain gap measured here is a question the engine-breadth field alone cannot answer. What it can say is that the gap is real and measured, not assumed.
What this changes for a search team
A single-surface AI visibility check — one ChatGPT prompt, one AI Overviews screenshot — is a sample of one engine's citation pool, not a market read. The practical implications:
- Checking AI Overviews tells a team nothing reliable about AI Mode citation status, and vice versa; treat them as two engines, not one line item.
- A "not cited by Google AI" conclusion needs both Google surfaces checked before it is safe to publish or act on internally.
- ChatGPT's narrower head overlap (72.2% of the top 500) means a domain's ChatGPT-citation status is the least representative single-engine signal of the six for judging overall AI citation reach.
- Perplexity and Claude's near-universal head overlap (98.0% and 92.6%) make either one, alone, a reasonable proxy for "is this domain in the general citation pool" — but neither substitutes for a same-surface Google read.
Method note
Figures are read directly from the Machine Relations Index's public release (machinerelations.ai/data/machine-relations-index.json, generated 2026-09-23, window 2026-05-10 to 2026-09-23, 130 days observed, 23,280 cited domains). The head-overlap table covers the 500 domains carrying a populated rank field — the only domains for which the release publishes a head ranking; the remaining 22,780 domains are ranked null in the public view and are outside this analysis. engine_breadth.engines records whether an engine cited a domain at least once in the window; it is not a citation rate and not a ranking weight. TechRadar's per-run and per-day figures are read from its own mri_score_v2.overall record in the same release. No Answer-Source Fidelity rate is used in this piece: Fidelity currently reports per-engine supported rates for ChatGPT, Claude, Gemini and Perplexity only, and does not yet cover either Google surface, so it cannot answer this question.
FAQ
Are Google AI Mode and Google AI Overviews the same product? No. They share underlying technology — Google's query fan-out approach and a Gemini model — but are different surfaces: AI Overviews are a passive summary layered on standard search results, while AI Mode is a separate, actively opened, multi-turn conversational experience.
Does a domain being absent from Google AI Overviews mean it has no AI citations at all? No. TechRadar.com is cited by four of the six measured engines (ChatGPT, Claude, Gemini, Perplexity) and ranks 7th of 23,280 cited domains overall, while being absent from both Google AI surfaces in this window.
Which engine has the widest reach into the most-cited domains? Perplexity, reaching 490 of the top 500 domains (98.0%) in this release. ChatGPT has the narrowest reach at 361 of 500 (72.2%).
Does this data show why the two Google surfaces cite different domains?
Not directly. The Index records which domains each engine cited, not why. Public documentation on Google's crawler-access controls (Google-Extended) describes one plausible mechanism, but confirming it would require access data Machine Relations does not publish.
Where does this data come from? The Machine Relations Index, an editorially independent research instrument from the team behind Paralax, refreshed on a rolling basis and covering six answer engines: ChatGPT, Claude, Gemini, Google AI Mode, Google AI Overviews and Perplexity.