DeepSeek V2.5 and GPT-5.1-Codex-Max don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. DeepSeek V2.5 shipped 444 days before GPT-5.1-Codex-Max, so benchmark comparisons should account for the intervening progress.

DeepSeek V2.5 is open weight, while GPT-5.1-Codex-Max is proprietary.

Direct benchmark comparisons are unavailable — DeepSeek V2.5 and GPT-5.1-Codex-Max don't publish scores on any of the same benchmarks.