How do diffusion language models work, and when would you use one over an autoregressive LLM?

Autoregressive models commit one token at a time, left to right. Diffusion language models generate the whole sequence at once and refine it over several denoising steps, which buys parallel decoding and global editing but has not yet caught the frontier. The signal is knowing the tradeoff, not just the buzzword.

Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.