Across 24 shared benchmarks, GPT-5.6 Terra scores higher on 2 and GPT-6 Astra on 22. The widest gap is OmniScience Non-Hallucination, where GPT-6 Astra scores 55.2 against 12.1. GPT-5.6 Terra is the cheaper of the two on tracked API pricing ($2.00 against $10.00 per million input tokens).
Best tracked score per model per benchmark (default configuration; source-attributed). ↓ marks lower-is-better metrics. Open either model for its full surface, provenance and pricing. Quoted rates are the price-setter row we currently track for each model — its direct or vendor-official listing where one exists (direct, direct), otherwise the lowest tracked offer.