What is the difference between Gemini 2.5 Flash Preview (thinking) and GPT-5 Codex?

Gemini 2.5 Flash Preview (thinking) is developed by Google AI while GPT-5 Codex is developed by OpenAI. You can compare their actual outputs across 19 challenges on Rival to see how they differ in practice.

Which is better, Gemini 2.5 Flash Preview (thinking) or GPT-5 Codex?

It depends on your use case. Gemini 2.5 Flash Preview (thinking) and GPT-5 Codex each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 19 challenges so you can judge which fits your needs best.

How can I compare Gemini 2.5 Flash Preview (thinking) and GPT-5 Codex on Rival?

This page shows a side-by-side comparison of Gemini 2.5 Flash Preview (thinking) and GPT-5 Codex across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.