Side-by-side benchmark comparison across agentic, coding, multimodal, knowledge, reasoning, and math workflows.
Step 3.5 Flash is clearly ahead on the aggregate, 66 to 48. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Step 3.5 Flash's sharpest advantage is in mathematics, where it averages 84.5 against 59.5. The single biggest benchmark swing on the page is MuSR, 82 to 47.
Step 3.5 Flash gives you the larger context window at 256K, compared with 128K for GPT-OSS 120B.
Pick Step 3.5 Flash if you want the stronger benchmark profile. GPT-OSS 120B only becomes the better choice if its workflow or ecosystem matters more than the raw scoreboard.
Step 3.5 Flash
60.2
GPT-OSS 120B
44.8
Step 3.5 Flash
47.1
GPT-OSS 120B
28.1
Step 3.5 Flash
66.7
GPT-OSS 120B
48.8
Step 3.5 Flash
78.3
GPT-OSS 120B
55.2
Step 3.5 Flash
60.8
GPT-OSS 120B
41.5
Step 3.5 Flash
87
GPT-OSS 120B
79
Step 3.5 Flash
82.8
GPT-OSS 120B
70.7
Step 3.5 Flash
84.5
GPT-OSS 120B
59.5
Step 3.5 Flash is ahead overall, 66 to 48. The biggest single separator in this matchup is MuSR, where the scores are 82 and 47.
Step 3.5 Flash has the edge for knowledge tasks in this comparison, averaging 60.8 versus 41.5. Inside this category, MMLU is the benchmark that creates the most daylight between them.
Step 3.5 Flash has the edge for coding in this comparison, averaging 47.1 versus 28.1. Inside this category, HumanEval is the benchmark that creates the most daylight between them.
Step 3.5 Flash has the edge for math in this comparison, averaging 84.5 versus 59.5. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.
Step 3.5 Flash has the edge for reasoning in this comparison, averaging 78.3 versus 55.2. Inside this category, MuSR is the benchmark that creates the most daylight between them.
Step 3.5 Flash has the edge for agentic tasks in this comparison, averaging 60.2 versus 44.8. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
Step 3.5 Flash has the edge for multimodal and grounded tasks in this comparison, averaging 66.7 versus 48.8. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.
Step 3.5 Flash has the edge for instruction following in this comparison, averaging 87 versus 79. Inside this category, IFEval is the benchmark that creates the most daylight between them.
Step 3.5 Flash has the edge for multilingual tasks in this comparison, averaging 82.8 versus 70.7. Inside this category, MGSM is the benchmark that creates the most daylight between them.
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