Comprehensive side-by-side LLM comparison
. Both models have their strengths depending on your specific coding needs.
OpenAI
GPT-5.1 Codex Max, released by OpenAI in November 2025, is an enhanced coding variant from the GPT-5.1 Codex line, designed for more complex software engineering tasks requiring additional reasoning depth. It targets large-scale code generation, automated refactoring, and sophisticated agentic development workflows.
NVIDIA
Llama-3.1-Nemotron-Ultra-253B-v1 is a 253-billion-parameter model from NVIDIA, derived from Meta's Llama 3.1 405B using neural architecture search (NAS) compression combined with NVIDIA's Nemotron post-training pipeline, which recovers and exceeds the base model's capability after structural compression. Released in April 2025, it supports toggling between a standard instruction mode and an extended reasoning mode via system prompt, allowing the same model to handle both rapid responses and deliberate chain-of-thought tasks. It is the flagship of the Nemotron family, available open-weight on HuggingFace and through NVIDIA NIM for enterprise inference.
6 months newer

Llama-3.1 Nemotron Ultra 253B
NVIDIA
2025-04-07

GPT-5.1 Codex Max
OpenAI
2025-11
Available providers and their performance metrics
GPT-5.1 Codex Max
Llama-3.1 Nemotron Ultra 253B
GPT-5.1 Codex Max
Llama-3.1 Nemotron Ultra 253B