Across 34 shared benchmarks, Claude Fable 5.1 scores higher on 34 and GPT-5.6 Luna on 0. The widest gap is GDP (Surge AI), where Claude Fable 5.1 scores 85.1 against 22.7. GPT-5.6 Luna is the cheaper of the two on tracked API pricing ($0.20 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.