Across 37 shared benchmarks, GPT-5.5 scores higher on 34 and Nemotron 3 Ultra 550B A55B on 3. The widest gap is critpt, where GPT-5.5 scores 27.1 against 3.1. Nemotron 3 Ultra 550B A55B is the cheaper of the two on tracked API pricing ($0.68 against $5.00 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.