Qwen 3 72B Instruct is the direct successor to Qwen 2.5 72B Instruct; both are dense 72B models from Alibaba, but the third-generation model ships with meaningful improvements. Qwen 3 72B pushes MMLU from ~86 (2.5) to ~89–90, gains a 128K context window (vs 32K for 2.5), and improves on math and coding benchmarks — HumanEval moves from ~86% to ~90%+. The price premium for Qwen 3 72B is real but modest: roughly $0.80–$1.40/M tokens vs $0.60–$1.10/M for Qwen 2.5 72B across major providers. For teams already running Qwen 2.5 72B, the migration path is straightforward — same tokenizer family, compatible prompt formats — so switching involves minimal integration overhead. **Where Qwen 2.5 72B wins:** workloads where the lower price is the primary driver and existing MMLU ~86 quality is already meeting SLA. It has broader provider availability and is more likely to be available on legacy GPU SKUs with proven uptime records. **Where Qwen 3 72B wins:** any workload pushing the boundaries of the 2.5 generation — longer documents that exceed 32K tokens, math and reasoning tasks where the accuracy delta matters, or new deployments where there's no sunk cost in the older model. Pick [Qwen 2.5 72B Instruct](/models/alibaba--qwen-2.5-72b-instruct) when you're already on it and the cost savings outweigh the quality increment. Pick [Qwen 3 72B Instruct](/models/alibaba--qwen-3-72b-instruct) for new deployments or any workload where the 128K context window or improved reasoning benchmarks pay off.