Mistral Medium 3.5 and GPT-5.6 Luna don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Mistral Medium 3.5 shipped 58 days before GPT-5.6 Luna, so benchmark comparisons should account for the intervening progress.

Mistral Medium 3.5 is open weight, while GPT-5.6 Luna is proprietary.

Direct benchmark comparisons are unavailable — Mistral Medium 3.5 and GPT-5.6 Luna don't publish scores on any of the same benchmarks.