Blog · 25 September 2026 · By HeardOf

AI Mode vs AI Overviews, and where Gemini fits: Google's AI surfaces in Google's own words

AI Mode vs AI Overviews: what is the difference?

AI Overviews is a generated summary that appears on some ordinary Google results pages; AI Mode is a separate search experience, reached from google.com/ai, an AI Mode control, or a follow-up from an overview, built for follow-up questions. That is how Google's own pages put it. Google's AI features guide for site owners, last updated 10 December 2025, historical, says "AI Overviews help people get to the gist of a complicated topic or question more quickly", and that "AI Overviews are only shown when our systems determine that it is additive to classic Search, and as such, often don't trigger." Of AI Mode, the same guide says it "is particularly helpful for queries where further exploration, reasoning, or complex comparisons are needed."

Google's help article on AI Mode, which carries no date as served and was read on 25 September 2026, calls it "Google's most powerful AI search experience" and says it "expands what AI Overviews can do with more advanced reasoning and ways of interacting." It is reached from google.com/ai, from an AI Mode control after a search, or from the Google app. It also says that "in some cases, AI Mode will provide a set of web links" instead of a response when Google is not confident in one.

The difference that matters for anyone comparing AI Mode vs AI Overviews in a report is in Google's AI features guide: "AI Mode and AI Overviews may use different models and techniques, so the set of responses and links they show will vary." Google's PDF on the two features, dated May 2025 on its cover, historical, says the same thing about the same query: "a different set of responses and links will likely appear".

Since May 2026 the two are joined at one point. Elizabeth Reid's I/O post of 19 May 2026, historical, says "You can easily ask a follow-up question right from an AI Overview, and flow into a conversational back and forth with AI Mode", and Google's list of I/O announcements of 20 May 2026, historical, describes the path as "from your question, to a search results page with an AI Overview, to a follow-up in AI Mode". An answer that starts as an overview can therefore continue in AI Mode.

Where does the Gemini app fit?

The Gemini app is a separate Google app, used at its own address rather than on a results page; "Gemini" is also the name Google gives the models under AI Overviews and AI Mode. Google's Gemini Apps help article, undated as served, tells you to "go to gemini.google.com" to start a chat. Google's overview of the Gemini app, which says it was "last updated on July 25, 2024", historical, describes the app as the one "which allows people to collaborate directly with generative AI", and says it "relies on external sources such as Google Search, and/or one of its several extensions" to write its responses, "known as retrieval augmentation".

Google's May 2025 PDF, historical, says "AI Overviews use a customized Gemini model" and that AI Mode runs on "a custom version of Gemini". So a report line reading "Gemini" can mean the app a person types into, a model called through Google's API, or, loosely, one of the Search features that model sits under. The name alone does not say which. Sundar Pichai's I/O post of 19 May 2026, historical, gives each of the three its own user figure, in the table above.

What is query fan-out, per Google?

Query fan-out is Google's name for turning one question into many searches run at once. The AI Mode help article says AI Mode "uses a “query fan-out” technique, dividing your question into subtopics and searching for each one simultaneously across multiple data sources. It then brings those results together". The AI features guide says "Both AI Overviews and AI Mode may use" it, so the technique is not only AI Mode's.

In Google's Ask a Techspert explainer of 5 March 2026, historical, Search Senior Engineering Director Dounia Berrada puts it as "AI Mode is basically doing a dozen searches for you in the time it takes to do one"; her subject there is visual search, where one photo becomes several searches. None of the Google pages we read lists the searches a given answer ran. Some AI visibility tools now sell a feature named for query fan-out, and query fan-out: what Google says it is, and which tools sell it lists them with the page each one names it on.

How do AI visibility tools split Google's surfaces?

The two we read, Semrush and Similarweb, list them differently, and Semrush lists the same feature differently on different pages: its Prompt Tracking names AI Overviews in knowledge base article 1607 and not on its AI visibility page. Asked directly, on pages as served on 25 September 2026, Semrush's FAQ answer to "What LLMs does Semrush track?" names six engines, among them Google AI Mode and Google AI Overviews, and Similarweb's answer to "Which AI chatbots and search platforms does Similarweb track?" names four for its AI Brand Visibility tracker, among them Google AI Mode and not AI Overviews. Across the twelve Semrush rows in the table below, from five pages, 9 name Google AI Mode, 6 name Google AI Overviews, 2 say only "Google AI", and the lists run from two names to six. These are names on a page, not coverage we tested.

Similarweb does name AI Overviews on its AEO page, in a different place: under its Rank Tracker and SERP features, "Measure your presence across all AI surfaces, including AI Overviews, Featured Snippets, and People Also Ask boxes", and "you can see how many of your tracked keywords are triggering AI Overviews". On that page AI Overviews is a feature a keyword triggers on a results page, and AI Mode is one of four platforms in the brand-visibility feature, which "currently includes AI Mode, ChatGPT, Gemini, and Perplexity". Why Similarweb groups them that way is not on the page.

On Semrush's knowledge base article 1607, "Prompt responses are captured from real requests and not via any APIs of LLMs". We make no claim about which Semrush feature reads which surface beyond what each sentence says.

Which of these does HeardOf check?

Google AI Overviews, and not AI Mode. Per our post on which engines we check, as updated 23 September 2026, we ask four engines, and the Google Search one is the AI Overview block on a Google results page, fetched for us by SerpAPI as a United States, English search; the same post calls AI Mode "a separate surface that is not on the list", as of 23 September 2026. A prompt for which Google shows no overview counts as an answer in which nobody was named, by the same post, as of 23 September 2026. Our Gemini engine is a Gemini model called through Google's API, as read on 19 September 2026: by this post's terms, a model, not the Gemini app a person types into, and not AI Mode.

Until 23 September 2026 our collection read no Google results page, as the same post says, and an earlier version of it said so at the time.

How was this read?

Every page named here was fetched on 25 September 2026 between 00:58 and 01:02 UTC with curl and a Chrome user-agent, in English, and read as served; the AI Mode help article, the AI features guide and our own post were fetched again between 03:12 and 03:13 UTC and the text quoted here had not changed. No page answered with a bot challenge. Our headless renders of the four vendor pages came back empty and were not used, so what we say about a vendor page is about the page as served. A headless render of the seven vendor pages by our reviewer at 03:21–03:22 UTC on 25 September 2026 showed the same engine-naming text. Dates are the ones printed on each page; historical means older than 90 days on the reading day.

What we could not do: the AI Mode help article carries no date, as served or in its structured data, so we cannot say when its wording was written; the Gemini app overview says it was last updated in July 2024 and still mentions "Gemini Advanced", so whether it describes today's app is not established; Gemini's own overview and about pages answered this network in Spanish without a country path, and we read the United States English page instead. We did not count how any vendor other than Semrush and Similarweb lists Google's surfaces. Everything this post says about our own system comes from our own systems and cannot be checked from here; the rest carries a link and the day it was read.

Query fan-out: what Google says it is, and how many AI visibility tools now sell it