BrightEdge has published a study showing that different types of sites five AI search surfaces tend to show in generated answers. The study compared the top cited website sources across AI engines to measure how much they overlap (Source Overlap). The study found that there was a wide discrepancy across the five AI surfaces, with the lowest level of overlapping source citations between any two surfaces at 16% and the highest level of agreement between any one of the five engines at 59%. The study also found that brands that are closely associated with products and services tend to perform similarly across most of the tested AI surfaces. The largest category overlap across all five search engines were found in citations of corporate brand, commercial, and editorial sites, with a low end of 37% on Gemini to as high as 51% on AI Overviews. Despite this, Gemini tended to link out to only the most trustworthy and authoritative websites. The difference between Gemini and Google AI overviews used as sources indicates that Gemini is more conservative, showing more trust toward institutional sites at a higher rate than UGC sites.