Comprehensive side-by-side LLM comparison
GPT-5.1 Thinking leads with 2.6% higher average benchmark score. GPT-5.1 Thinking supports multimodal inputs. Both models have their strengths depending on your specific coding needs.
OpenAI
GPT-5.1 Codex, released by OpenAI in November 2025, is a coding-specialized model from the GPT-5.1 family engineered for software engineering tasks including code generation, multi-file editing, and agentic development. It targets developers and automated coding pipelines requiring a GPT-5.1-generation model tuned for programming.
OpenAI
GPT-5.1 Thinking, released by OpenAI in November 2025, is an extended reasoning variant from the GPT-5.1 family that applies chain-of-thought processing to improve accuracy on complex reasoning, mathematics, and coding tasks. It targets analytical workflows where deliberate reasoning over a problem significantly improves output quality.
Launched on the same date

GPT-5.1 Codex
OpenAI
2025-11

GPT-5.1 Thinking
OpenAI
2025-11
Average performance across 1 common benchmarks
GPT-5.1 Codex
GPT-5.1 Thinking
Performance comparison across key benchmark categories
GPT-5.1 Codex
GPT-5.1 Thinking
Available providers and their performance metrics
GPT-5.1 Codex
GPT-5.1 Thinking
GPT-5.1 Codex
GPT-5.1 Thinking