Ahrefs: Google AI Mode & Overviews Cite Different Sources

A new report from Ahrefs reveals a significant divergence in how Google's generative AI features—AI Mode and AI Overviews—source information, even when providing semantically similar answers. Despite often agreeing on the core message, these distinct AI experiences frequently cite different URLs and content types, a finding with notable implications for SEO professionals and content creators.

Ahrefs Study Uncovers Key Differences

The analysis, published on the Ahrefs blog, utilized recent U.S. data analyzed in September from Ahrefs' Brand Radar tool. It meticulously compared responses from AI Mode and AI Overviews for identical search queries. Researchers examined 730,000 query pairs for content similarity and 540,000 for citation and URL analysis.

Ahrefs found that AI Mode and AI Overviews cited the exact same URLs in only 13% of cases. Even when focusing on the top three citations within each response, the overlap merely increased to 16%.

While the language used in responses also varied—with only a 16% overlap in unique words and the exact same first sentence appearing just 2.5% of the time—the study reported strong semantic alignment. The average semantic similarity score was an impressive 86%, with 89% of response pairs scoring above 0.8 (where 1.0 signifies identical meaning).

Despina Gavoyannis, Senior SEO Specialist at Ahrefs, succinctly summarized the findings:

“Put simply: 9 out of 10 times, AI Mode and AI Overview agreed on what to say. They just said it differently and cited different sources.”

Different Source Preferences Emerge

The report further detailed distinct preferences in the types of websites and content each Google AI feature tends to cite.

For instance, Wikipedia appeared in 28.9% of AI Mode citations, significantly higher than its 18.1% presence in AI Overviews. AI Mode also cited Quora 3.5 times more frequently and referenced health-related sites at roughly double the rate of AI Overviews.

Conversely, AI Overviews showed a stronger inclination towards video content, with YouTube emerging as its most frequently cited source. Reddit, however, was cited at similar rates across both AI Mode and AI Overviews.

Ahrefs also observed that AI Overviews cited videos and core pages (like homepages) nearly twice as often as AI Mode. Despite these differences, both features demonstrated a strong overall preference for article-format pages.

Entity and Brand Mentions Vary

Ahrefs' analysis also highlighted differences in response length and entity mentions. AI Mode responses were, on average, about four times longer than AI Overviews and included more entities.

In the dataset, AI Mode averaged 3.3 entity mentions per response compared to 1.3 for AI Overviews. Approximately 61% of the time, AI Mode not only included all entities mentioned in the AI Overview response but also added additional ones.

Interestingly, many responses from both features did not include brands or entities. Ahrefs reported that 59.41% of AI Overview responses and 34.66% of AI Mode responses contained no mentions of persons or brands. The authors attribute this to informational queries where named entities are not typically part of the answer.

Citation Gaps Identified

The data also indicated that AI Mode was more likely to include citations than AI Overviews.

Only 3% of AI Mode responses lacked sources, compared to 11% of AI Overviews. Ahrefs notes that missing citations typically occur in specific scenarios, such as calculations, sensitive queries, redirects to help centers, or unsupported languages.

Why This Matters for SEO Visibility

This comprehensive report underscores that Google's AI Mode and AI Overviews can significantly differ in their credited sources, even when delivering similar conclusions for the same query. This divergence has crucial implications for SEO monitoring and understanding 'visibility' across these distinct AI experiences.

A citation or mention within AI Overviews does not guarantee a similar inclusion in AI Mode for the same query. Furthermore, AI Mode's typically longer responses may introduce additional entities and competitors compared to the more concise AI Overview format.

Google's own documentation states that both AI Overviews and AI Mode may employ 'query fan-out,' which involves issuing multiple related searches across various subtopics and data sources during response generation. Google also clarifies that AI Mode and AI Overviews may utilize different models and techniques, leading to variations in the responses and links they display.

Looking Ahead

Ahrefs cautions that this analysis compares single generations of AI Mode and AI Overview responses. In related research, Ahrefs previously reported that 45.5% of AI Overview citations change when these overviews update, suggesting that overlap could vary across repeated runs.

Even with this caveat, the consistently low overlap observed in the current dataset strongly indicates that AI Mode and AI Overviews frequently select different URLs as supporting sources for identical queries, a critical insight for anyone tracking AI-driven search performance.