Gemini Diffusion vs GPT-5.2 Codex

Gemini Diffusion

Google DeepMind

Gemini Diffusion is an experimental text and code generation model from Google DeepMind, announced at Google I/O in May 2025 as the first diffusion-based language model to achieve quality comparable to autoregressive models on standard benchmarks. Unlike transformer-based models that predict tokens sequentially left-to-right, it generates entire blocks of text by iteratively refining noise — the paradigm used in image and video generation models — enabling faster sampling speeds and stronger mid-generation error correction for code and mathematical editing tasks. At announcement it was available only as an experimental demo via waitlist, with no public API, marking it as a research milestone rather than a production deployment.

GPT-5.2 Codex

OpenAI

GPT-5.2 Codex is a coding-specialized variant from the GPT-5.2 family, designed for software engineering workflows including automated code generation, multi-file editing, and agentic development. It builds on GPT-5.2's improved instruction following and long-context capabilities, with optimizations specifically targeting programming tasks and agentic software workflows.