Head-to-head comparison across 2benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
DeepSeek V4 Flash (High)
71
GPT-5.5 Pro
100
Verified leaderboard positions: DeepSeek V4 Flash (High) #19 · GPT-5.5 Pro unranked
Pick GPT-5.5 Pro if you want the stronger benchmark profile. DeepSeek V4 Flash (High) only becomes the better choice if you want the cheaper token bill.
Agentic
+34.7 difference
Knowledge
DeepSeek V4 Flash (High)
GPT-5.5 Pro
$0.14 / $0.28
$30 / $180
N/A
N/A
N/A
N/A
1M
1M
Pick GPT-5.5 Pro if you want the stronger benchmark profile. DeepSeek V4 Flash (High) only becomes the better choice if you want the cheaper token bill.
GPT-5.5 Pro is clearly ahead on the provisional aggregate, 100 to 71. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.5 Pro's sharpest advantage is in agentic, where it averages 90.1 against 55.4. The single biggest benchmark swing on the page is BrowseComp, 53.5% to 90.1%.
GPT-5.5 Pro is also the more expensive model on tokens at $30.00 input / $180.00 output per 1M tokens, versus $0.14 input / $0.28 output per 1M tokens for DeepSeek V4 Flash (High). That is roughly 642.9x on output cost alone.
GPT-5.5 Pro is ahead on BenchLM's provisional leaderboard, 100 to 71. The biggest single separator in this matchup is BrowseComp, where the scores are 53.5% and 90.1%.
DeepSeek V4 Flash (High) and GPT-5.5 Pro are effectively tied for knowledge tasks here, both landing at 57.2 on average.
GPT-5.5 Pro has the edge for agentic tasks in this comparison, averaging 90.1 versus 55.4. Inside this category, BrowseComp is the benchmark that creates the most daylight between them.
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