Head-to-head comparison across 2benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Claude Sonnet 4.5
65
Mellum2-12B-A2.5B-Instruct
27
Pick Claude Sonnet 4.5 if you want the stronger benchmark profile. Mellum2-12B-A2.5B-Instruct only becomes the better choice if its workflow or ecosystem matters more than the raw scoreboard.
Coding
+40.0 difference
Knowledge
+42.5 difference
Claude Sonnet 4.5
Mellum2-12B-A2.5B-Instruct
$3 / $15
N/A
N/A
N/A
N/A
N/A
200K
128K
Pick Claude Sonnet 4.5 if you want the stronger benchmark profile. Mellum2-12B-A2.5B-Instruct only becomes the better choice if its workflow or ecosystem matters more than the raw scoreboard.
Claude Sonnet 4.5 is clearly ahead on the provisional aggregate, 65 to 27. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Claude Sonnet 4.5's sharpest advantage is in knowledge, where it averages 83.4 against 40.9. The single biggest benchmark swing on the page is GPQA, 83.4% to 40.9%.
Claude Sonnet 4.5 gives you the larger context window at 200K, compared with 128K for Mellum2-12B-A2.5B-Instruct.
Claude Sonnet 4.5 is ahead on BenchLM's provisional leaderboard, 65 to 27. The biggest single separator in this matchup is GPQA, where the scores are 83.4% and 40.9%.
Claude Sonnet 4.5 has the edge for knowledge tasks in this comparison, averaging 83.4 versus 40.9. Inside this category, GPQA is the benchmark that creates the most daylight between them.
Claude Sonnet 4.5 has the edge for coding in this comparison, averaging 77.2 versus 37.2. Mellum2-12B-A2.5B-Instruct stays close enough that the answer can still flip depending on your workload.
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