Claude Opus 4.1 vs Phi-3.5-MoE Instruct

Claude Opus 4.1

Anthropic

Claude Opus 4.1, released by Anthropic in August 2025, is a large language model from the Claude 4 family optimized for demanding reasoning, multi-step coding, and extended analysis tasks. It features a 200K token context window, 32K maximum output tokens, native image understanding, and extended thinking capabilities. Opus 4.1 targets complex problem-solving, multi-turn reasoning workflows, and applications requiring deep analysis with integrated tool use.

Phi-3.5-MoE Instruct

Microsoft

Phi-3.5-MoE-instruct is a sparse mixture-of-experts model from Microsoft's Phi research team, released in August 2024 with 42 billion total parameters across 16 experts and approximately 6.6 billion active parameters per forward pass. The model applies Microsoft's small-data, high-quality training philosophy — developed across earlier Phi generations — to a MoE architecture, targeting reasoning quality comparable to much larger dense models at a fraction of the inference compute. Released under the MIT license, it was notable in the research community for demonstrating that MoE efficiency gains could be realized at smaller total parameter counts than typical large-scale MoE deployments.