Gemini 2.5 Flash vs Gemini 3.1 Pro

Gemini 2.5 Flash

Google DeepMind

Gemini 2.5 Flash, released by Google in June 2025, is a large language model from the Gemini 2.5 family optimized for high-throughput, cost-efficient deployments with multimodal reasoning. It features a 1M token context window, hybrid thinking control, and native support for text, image, video, and audio input. Gemini 2.5 Flash targets latency-sensitive applications, document analysis, and high-volume API workloads that benefit from combined reasoning and generation in a single model.

Gemini 3.1 Pro

Google DeepMind

Gemini 3.1 Pro is a multimodal language model from Google DeepMind, released in preview in February 2026 as a point-version upgrade to Gemini 3 Pro focused on improving reasoning depth, factual grounding, and coding and agentic task performance. The model accepts text, images, video, audio, and PDFs as inputs across a 1M token context window, extending the multimodal breadth of the Gemini 3 series with a companion endpoint specifically optimized for custom tool use in agentic pipelines. Google describes it as built to refine the reliability and performance of the Gemini 3 Pro series, reflecting an incremental engineering iteration rather than an architectural overhaul.