Head-to-head comparison across 3benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
DeepSeek V4 Flash Base
31
Qwen3.5 397B
64
Verified leaderboard positions: DeepSeek V4 Flash Base unranked · Qwen3.5 397B #14
Pick Qwen3.5 397B if you want the stronger benchmark profile. DeepSeek V4 Flash Base only becomes the better choice if multilingual is the priority or you need the larger 1M context window.
Reasoning
+18.5 difference
Knowledge
+13.0 difference
Multilingual
+1.0 difference
DeepSeek V4 Flash Base
Qwen3.5 397B
$null / $null
$0.6 / $3.6
N/A
96 t/s
N/A
2.44s
1M
128K
Pick Qwen3.5 397B if you want the stronger benchmark profile. DeepSeek V4 Flash Base only becomes the better choice if multilingual is the priority or you need the larger 1M context window.
Qwen3.5 397B is clearly ahead on the provisional aggregate, 64 to 31. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Qwen3.5 397B's sharpest advantage is in reasoning, where it averages 63.2 against 44.7. The single biggest benchmark swing on the page is SuperGPQA, 46.5% to 70.4%. DeepSeek V4 Flash Base does hit back in multilingual, so the answer changes if that is the part of the workload you care about most.
DeepSeek V4 Flash Base gives you the larger context window at 1M, compared with 128K for Qwen3.5 397B.
Qwen3.5 397B is ahead on BenchLM's provisional leaderboard, 64 to 31. The biggest single separator in this matchup is SuperGPQA, where the scores are 46.5% and 70.4%.
Qwen3.5 397B has the edge for knowledge tasks in this comparison, averaging 65.2 versus 52.2. Inside this category, SuperGPQA is the benchmark that creates the most daylight between them.
Qwen3.5 397B has the edge for reasoning in this comparison, averaging 63.2 versus 44.7. Inside this category, LongBench v2 is the benchmark that creates the most daylight between them.
DeepSeek V4 Flash Base has the edge for multilingual tasks in this comparison, averaging 85.7 versus 84.7. Qwen3.5 397B stays close enough that the answer can still flip depending on your workload.
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