GPT-5.3-Codex-Spark vs Qwen3.5 397B (Reasoning)

Side-by-side benchmark comparison across agentic, coding, multimodal, knowledge, reasoning, and math workflows.

GPT-5.3-Codex-Spark is clearly ahead on the aggregate, 87 to 75. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

GPT-5.3-Codex-Spark's sharpest advantage is in coding, where it averages 82.3 against 62.3. The single biggest benchmark swing on the page is MMMU-Pro, 86 to 64.

GPT-5.3-Codex-Spark gives you the larger context window at 256K, compared with 128K for Qwen3.5 397B (Reasoning).

Quick Verdict

Pick GPT-5.3-Codex-Spark if you want the stronger benchmark profile. Qwen3.5 397B (Reasoning) only becomes the better choice if its workflow or ecosystem matters more than the raw scoreboard.

Agentic

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

85.6

Qwen3.5 397B (Reasoning)

74.8

90
Terminal-Bench 2.0
77
82
BrowseComp
78
83
OSWorld-Verified
70

Coding

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

82.3

Qwen3.5 397B (Reasoning)

62.3

91
HumanEval
83
80
SWE-bench Verified
60
80
LiveCodeBench
60
85
SWE-bench Pro
65

Multimodal & Grounded

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

88.3

Qwen3.5 397B (Reasoning)

70.8

86
MMMU-Pro
64
91
OfficeQA Pro
79

Reasoning

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

92.7

Qwen3.5 397B (Reasoning)

84.2

94
SimpleQA
87
92
MuSR
85
97
BBH
91
91
LongBench v2
80
92
MRCRv2
82

Knowledge

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

78.3

Qwen3.5 397B (Reasoning)

70.1

97
MMLU
91
95
GPQA
89
93
SuperGPQA
87
91
OpenBookQA
85
88
MMLU-Pro
81
42
HLE
29
88
FrontierScience
81

Instruction Following

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

92

Qwen3.5 397B (Reasoning)

89

92
IFEval
89

Multilingual

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

90.8

Qwen3.5 397B (Reasoning)

87.8

94
MGSM
91
89
MMLU-ProX
86

Mathematics

GPT-5.3-Codex-Spark

GPT-5.3-Codex-Spark

96.7

Qwen3.5 397B (Reasoning)

92.5

98
AIME 2023
93
98
AIME 2024
95
97
AIME 2025
94
94
HMMT Feb 2023
89
96
HMMT Feb 2024
91
95
HMMT Feb 2025
90
95
BRUMO 2025
92
98
MATH-500
93

Frequently Asked Questions

Which is better, GPT-5.3-Codex-Spark or Qwen3.5 397B (Reasoning)?

GPT-5.3-Codex-Spark is ahead overall, 87 to 75. The biggest single separator in this matchup is MMMU-Pro, where the scores are 86 and 64.

Which is better for knowledge tasks, GPT-5.3-Codex-Spark or Qwen3.5 397B (Reasoning)?

GPT-5.3-Codex-Spark has the edge for knowledge tasks in this comparison, averaging 78.3 versus 70.1. Inside this category, HLE is the benchmark that creates the most daylight between them.

Which is better for coding, GPT-5.3-Codex-Spark or Qwen3.5 397B (Reasoning)?

GPT-5.3-Codex-Spark has the edge for coding in this comparison, averaging 82.3 versus 62.3. Inside this category, SWE-bench Verified is the benchmark that creates the most daylight between them.

Which is better for math, GPT-5.3-Codex-Spark or Qwen3.5 397B (Reasoning)?

GPT-5.3-Codex-Spark has the edge for math in this comparison, averaging 96.7 versus 92.5. Inside this category, AIME 2023 is the benchmark that creates the most daylight between them.

Which is better for reasoning, GPT-5.3-Codex-Spark or Qwen3.5 397B (Reasoning)?

GPT-5.3-Codex-Spark has the edge for reasoning in this comparison, averaging 92.7 versus 84.2. Inside this category, LongBench v2 is the benchmark that creates the most daylight between them.

Which is better for agentic tasks, GPT-5.3-Codex-Spark or Qwen3.5 397B (Reasoning)?

GPT-5.3-Codex-Spark has the edge for agentic tasks in this comparison, averaging 85.6 versus 74.8. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.

Which is better for multimodal and grounded tasks, GPT-5.3-Codex-Spark or Qwen3.5 397B (Reasoning)?

GPT-5.3-Codex-Spark has the edge for multimodal and grounded tasks in this comparison, averaging 88.3 versus 70.8. Inside this category, MMMU-Pro is the benchmark that creates the most daylight between them.

Which is better for instruction following, GPT-5.3-Codex-Spark or Qwen3.5 397B (Reasoning)?

GPT-5.3-Codex-Spark has the edge for instruction following in this comparison, averaging 92 versus 89. Inside this category, IFEval is the benchmark that creates the most daylight between them.

Which is better for multilingual tasks, GPT-5.3-Codex-Spark or Qwen3.5 397B (Reasoning)?

GPT-5.3-Codex-Spark has the edge for multilingual tasks in this comparison, averaging 90.8 versus 87.8. Inside this category, MGSM is the benchmark that creates the most daylight between them.

Last updated: March 12, 2026

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