Head-to-head comparison across 3benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Mellum2-12B-A2.5B-Instruct
27
Qwen3.5-27B
62
Verified leaderboard positions: Mellum2-12B-A2.5B-Instruct unranked · Qwen3.5-27B #21
Pick Qwen3.5-27B if you want the stronger benchmark profile. Mellum2-12B-A2.5B-Instruct only becomes the better choice if you would rather avoid the extra latency and token burn of a reasoning model.
Coding
+25.8 difference
Knowledge
+39.7 difference
Inst. Following
+19.2 difference
Mellum2-12B-A2.5B-Instruct
Qwen3.5-27B
N/A
$0 / $0
N/A
N/A
N/A
N/A
128K
262K
Pick Qwen3.5-27B if you want the stronger benchmark profile. Mellum2-12B-A2.5B-Instruct only becomes the better choice if you would rather avoid the extra latency and token burn of a reasoning model.
Qwen3.5-27B is clearly ahead on the provisional aggregate, 62 to 27. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Qwen3.5-27B's sharpest advantage is in knowledge, where it averages 80.6 against 40.9. The single biggest benchmark swing on the page is GPQA, 40.9% to 85.5%.
Qwen3.5-27B is the reasoning model in the pair, while Mellum2-12B-A2.5B-Instruct 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. Qwen3.5-27B gives you the larger context window at 262K, compared with 128K for Mellum2-12B-A2.5B-Instruct.
Qwen3.5-27B is ahead on BenchLM's provisional leaderboard, 62 to 27. The biggest single separator in this matchup is GPQA, where the scores are 40.9% and 85.5%.
Qwen3.5-27B has the edge for knowledge tasks in this comparison, averaging 80.6 versus 40.9. Inside this category, GPQA is the benchmark that creates the most daylight between them.
Qwen3.5-27B has the edge for coding in this comparison, averaging 63 versus 37.2. Mellum2-12B-A2.5B-Instruct stays close enough that the answer can still flip depending on your workload.
Qwen3.5-27B has the edge for instruction following in this comparison, averaging 95 versus 75.8. Inside this category, IFEval is the benchmark that creates the most daylight between them.
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