> ## Documentation Index
> Fetch the complete documentation index at: https://docs.peec.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Optimizing for Google AI Overviews and AI Mode vs ChatGPT — 5 differences

> Peec's research (2026) — Google's AI surfaces promote YouTube and render JavaScript; ChatGPT runs on Bing with RRF fan-outs, skips JS, and leans on English sources; both lean heavily on Reddit.

Google's AI ecosystem (AI Overviews, AI Mode, Gemini) and ChatGPT use different ranking signals, trust different sources, and reward different optimization strategies. Peec's 500,000-prompt AI Overviews study ([full study](https://peec.ai/blog/ai-overviews-is-the-most-undertracked-ai-search-500-000-prompts-show-why), published 2026) names five differences, drawing on Peec's earlier 30-million-source analysis:

1. **AI Overviews heavily promotes YouTube.** Video content is a direct pathway into Google's AI surfaces that ChatGPT does not offer — see [YouTube in AI search](/research/youtube-in-ai-search).
2. **ChatGPT does not render JavaScript.** JS-heavy sites (React, Vue) are unreadable to ChatGPT but readable to Google — a structural advantage for AI Overviews on JS stacks.
3. **ChatGPT uses Reciprocal Rank Fusion (RRF).** It fans your prompt out into multiple sub-queries and combines results, so winning means appearing across many related queries, not ranking for one — see [What is a query fan-out](/research/what-is-a-query-fanout).
4. **Both ecosystems lean heavily on Reddit.** The one consistent signal across both — see [Reddit in AI search](/research/reddit-in-ai-search).
5. **Non-English markets are harder in ChatGPT.** ChatGPT mixes English and local-language sources even for non-English prompts, while AI Overviews stays closer to the query language — see [ChatGPT searches in English](/research/chatgpt-searches-in-english).

The two systems share some signals (Reddit presence, content quality, citations) but diverge enough that one combined strategy underperforms on both; the study recommends separate tracking and optimization per surface.

**Source:** [AI Overviews is the most undertracked AI search: 500,000 prompts show why](https://peec.ai/blog/ai-overviews-is-the-most-undertracked-ai-search-500-000-prompts-show-why), Peec (Tomek Rudzki), May 2026.