Gemma 2 and GPT-5-Codex-Mini don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Gemma 2 shipped 499 days before GPT-5-Codex-Mini, so benchmark comparisons should account for the intervening progress.

Gemma 2 is open weight, while GPT-5-Codex-Mini is proprietary.

Direct benchmark comparisons are unavailable — Gemma 2 and GPT-5-Codex-Mini don't publish scores on any of the same benchmarks.