Verdict
Gemini 3.8 Flash leads 12–5 across 17 shared benchmarks.
Gemini 3.1 Pro 5 · Gemini 3.8 Flash 12 · higher isn't always better — check the caveats below.
Reported scores — protocols may differ. How we compare
Unknown: Gemini 3.8 Flash leads 3–2 across 5 shared unknown benchmarks (largest gap: ProofBench, 48 vs 26 — single evaluator).
Reasoning: Evenly split 2–2 across 4 shared reasoning benchmarks (largest gap: SimpleQA Verified, 73.5 vs 69.7 — protocols undisclosed).
Math: Evenly split 1–1 across 2 shared math benchmarks (largest gap: FrontierMath-Tier-4-v2-Private, 26.83 vs 21.95 — protocols undisclosed).
Vendor claims — compare against the measured scores above. A claim is what a developer says about its own model, not an independent measurement.
Agentic / Tool Use
“Gemini 3.1 Pro was evaluated across a range of benchmarks, including reasoning, multimodal capabilities, agentic tool use, multi-lingual performance, and long-context.”
Multimodal
“a suite of highly capable, natively multimodal reasoning models”
Reasoning
“Gemini 3.1 Pro is Google's most advanced model for complex tasks.”
No vendor claims on file for Gemini 3.8 Flash.
Gemini 3.8 Flash leads 12–5 across 17 shared benchmarks. Gemini 3.1 Pro leads 5 benchmarks and Gemini 3.8 Flash leads 12. Higher isn't always better — see the integrity caveats on each benchmark.
Gemini 3.1 Pro and Gemini 3.8 Flash have 17 benchmarks in common in our data — those are the only rows where a direct, apples-to-apples comparison is drawn.
Gemini 3.8 Flash leads unknown 3–2.