Model comparison
Mellum2-12B-A2.5B-Thinking vs Qwen3.5 397B
Head-to-head evidence from 3 shared benchmark results across 2 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Mellum2-12B-A2.5B-Thinking unranked (Not scored); Qwen3.5 397B #71 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Mellum2-12B-A2.5B-Thinking and Qwen3.5 397B share 3 comparable benchmark results. 2 of 8 categories are comparable. 2 results are unique to Mellum2-12B-A2.5B-Thinking; 52 to Qwen3.5 397B.
Updated July 23, 2026- Shared results
- 3
- Mellum2-12B-A2.5B-Thinking only
- 2
- Qwen3.5 397B only
- 52
- Comparable categories
- 2 / 8
Treat this as a split decision. Mellum2-12B-A2.5B-Thinking makes more sense if knowledge is the priority or you want the stronger reasoning-first profile; Qwen3.5 397B is the better fit if instruction following is the priority or you would rather avoid the extra latency and token burn of a reasoning model.
Confidence note. This is a partial-evidence comparison with 3 shared benchmark results across 2 evidence categories; 2 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
Mellum2-12B-A2.5B-Thinking and Qwen3.5 397B finish on the same BenchAlign overall score, so this is less about a single winner and more about where the edge shows up. The BenchAlign headline says tie; the benchmark table is where the real choice happens.
Mellum2-12B-A2.5B-Thinking is the reasoning model in the pair, while Qwen3.5 397B is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
| Category | Mellum2-12B-A2.5B-Thinking | Δ | Qwen3.5 397B |
|---|---|---|---|
| Inst. Following | Mellum2-12B-A2.5B-Thinking76.5 | Margin→ 16.1 | Qwen3.5 397B92.6 |
| Knowledge | Mellum2-12B-A2.5B-Thinking57.6 | Margin← 1.0 | Qwen3.5 397B56.6 |
| Agentic | Mellum2-12B-A2.5B-ThinkingNot measured | MarginNo overlap | Qwen3.5 397B56.5 |
| Coding | Mellum2-12B-A2.5B-ThinkingNot measured | MarginNo overlap | Qwen3.5 397B66.5 |
| Reasoning | Mellum2-12B-A2.5B-ThinkingNot measured | MarginNo overlap | Qwen3.5 397B63.2 |
| Math | Mellum2-12B-A2.5B-ThinkingNot measured | MarginNo overlap | Qwen3.5 397B90.6 |
| Multilingual | Mellum2-12B-A2.5B-ThinkingNot measured | MarginNo overlap | Qwen3.5 397B84.7 |
| Multimodal | Mellum2-12B-A2.5B-ThinkingNot measured | MarginNo overlap | Qwen3.5 397B79.6 |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
GPQA
KnowledgeA 57.6%B 88.4%Winner: Qwen3.5 397BΔ 30.8GPQA: Mellum2-12B-A2.5B-Thinking scored 57.6%; Qwen3.5 397B scored 88.4%. Qwen3.5 397B wins this benchmark. - Source ↗
IFEval
Inst. FollowingA 76.5%B 92.6%Winner: Qwen3.5 397BΔ 16.1IFEval: Mellum2-12B-A2.5B-Thinking scored 76.5%; Qwen3.5 397B scored 92.6%. Qwen3.5 397B wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Mellum2-12B-A2.5B-Thinking | Qwen3.5 397B | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Mellum2-12B-A2.5B-ThinkingNot available | Qwen3.5 397B$0.6 input / $3.6 output | A complete price comparison is not available. |
| Generation speedtokens per second | Mellum2-12B-A2.5B-ThinkingNot available | Qwen3.5 397B96 tok/s | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Mellum2-12B-A2.5B-ThinkingNot available | Qwen3.5 397B2.44 s | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Mellum2-12B-A2.5B-Thinking128K | Qwen3.5 397B128K | Listed context windows are equal. |
Benchmark Deep Dive
Agentic19 benchmarks
| Benchmark | Mellum2-12B-A2.5B-Thinking | Qwen3.5 397B | Result |
|---|---|---|---|
| BFCL v4Source | 45.6% | — | Not comparable |
| Terminal-Bench 2.0Source | — | 52.5% | Not comparable |
| BrowseCompSource | — | 62% | Not comparable |
| Claw-EvalSource | — | 56.8% | Not comparable |
| QwenClawBenchSource | — | 51.8% | Not comparable |
| τ³-bench resultsSource | — | 68.4% | Not comparable |
| VITA-BenchSource | — | 43.7% | Not comparable |
| DeepPlanningSource | — | 37.6% | Not comparable |
| ToolathlonSource | — | 36.3% | Not comparable |
| MCP AtlasSource | — | 46.1% | Not comparable |
| MCP-TasksSource | — | 74.2% | Not comparable |
| WideResearchSource | — | 74.0% | Not comparable |
| τ²-bench resultsSource | — | 95.6% | Not comparable |
| Gert LabsSource | — | 46.76% | Not comparable |
| ResearchClawBenchSource | — | 14.2% | Not comparable |
| AA Agentic IndexSource | — | 19.9% | Not comparable |
| APEX-Agents-AASource | — | 15.3% | Not comparable |
| GDPval-AASource | — | 23.1% | Not comparable |
| GDPval-AASource | — | 962 | Not comparable |
Coding5 benchmarks
Reasoning4 benchmarks
KnowledgeMellum2-12B-A2.5B-Thinking wins13 benchmarks
| Benchmark | Mellum2-12B-A2.5B-Thinking | Qwen3.5 397B | Result |
|---|---|---|---|
| MMLU-ReduxSource | 86.2% | 94.9% | Qwen3.5 397B leads |
| GPQASource | 57.6% | 88.4% | Qwen3.5 397B leads |
| GPQA-DSource | 57.6% | — | Not comparable |
| SuperGPQASource | — | 70.4% | Not comparable |
| MMLU-ProSource | — | 87.8% | Not comparable |
| C-EvalSource | — | 93% | Not comparable |
| HLESource | — | 28.7% | Not comparable |
| Artificial Analysis Intelligence IndexSource | — | 33.7% | Not comparable |
| AA-GPQA DiamondSource | — | 89.3% | Not comparable |
| AA-HLESource | — | 27.3% | Not comparable |
| AA-Omniscience IndexSource | — | -29.8% | Not comparable |
| AA-Omniscience AccuracySource | — | 31.4% | Not comparable |
| AA-Omniscience Hallucination RateSource | — | 89.1% | Not comparable |
Math5 benchmarks
Multilingual2 benchmarks
Multimodal7 benchmarks
| Benchmark | Mellum2-12B-A2.5B-Thinking | Qwen3.5 397B | Result |
|---|---|---|---|
| MMMU-ProSource | — | 79% | Not comparable |
| MathVisionSource | — | 88.6% | Not comparable |
| CharXivSource | — | 80.8% | Not comparable |
| VideoMMMUSource | — | 84.7% | Not comparable |
| ScreenSpot ProSource | — | 65.6% | Not comparable |
| V*Source | — | 95.8% | Not comparable |
| AA-MMMU-ProSource | — | 77.3% | Not comparable |
Frequently Asked Questions (3)
Which is better, Mellum2-12B-A2.5B-Thinking or Qwen3.5 397B?
Mellum2-12B-A2.5B-Thinking and Qwen3.5 397B are tied on the BenchAlign overall score, so the right pick depends on which category matters most for your use case.
Which is better for knowledge tasks, Mellum2-12B-A2.5B-Thinking or Qwen3.5 397B?
Mellum2-12B-A2.5B-Thinking has the edge for knowledge tasks in this comparison, averaging 57.6 versus 56.6. Inside this category, GPQA is the benchmark that creates the most daylight between them.
Which is better for instruction following, Mellum2-12B-A2.5B-Thinking or Qwen3.5 397B?
Qwen3.5 397B has the edge for instruction following in this comparison, averaging 92.6 versus 76.5. Inside this category, IFEval is the benchmark that creates the most daylight between them.
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