GPT-5 Mini vs Phi-3.5-MoE Instruct

GPT-5 Mini

OpenAI

GPT-5 mini, released by OpenAI in August 2025, is a smaller variant from the GPT-5 family that inherits GPT-5's unified reasoning architecture and multimodal capabilities at a reduced inference cost. It targets high-volume production use cases requiring a balance of intelligence and response speed, offering GPT-5 capabilities for applications where full GPT-5 inference costs are a concern.

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.