o3 mini vs Phi-3.5-MoE Instruct

o3 mini

OpenAI

OpenAI o3 mini, released by OpenAI in January 2025, is a compact reasoning model from the o3 family designed for efficient, cost-effective STEM problem-solving. It features a 200K token context window and adjustable chain-of-thought effort settings, allowing developers to trade reasoning depth for speed. o3 mini targets science, mathematics, and coding applications where lower inference cost and faster response times are a priority.

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.