Model Comparison

Seed 2.1 Pro vs GPT-5.6 TerraWhich is better in 2026?

GPT-5.6 Terra significantly outperforms across most benchmarks.

Verdict: Seed 2.1 Pro vs GPT-5.6 Terra — which is better?

Seed 2.1 Pro (by ByteDance) and GPT-5.6 Terra (by OpenAI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.

Seed 2.1 Pro outperforms in 1 benchmarks (MMMU-Pro), while GPT-5.6 Terra is better at 6 benchmarks (Agents' Last Exam, BrowseComp, DeepSWE, SWE-Bench Pro, Terminal-Bench 2.1, Toolathlon). GPT-5.6 Terra significantly outperforms across most benchmarks.

Choose Seed 2.1 Pro if…

  • you are already invested in the ByteDance ecosystem

Choose GPT-5.6 Terra if…

  • you want the strongest raw capability — it leads on 6 of 7 shared benchmarks
  • you want the most recent training data — it shipped Jul 2026

Performance Benchmarks

Comparative analysis across standard metrics

7 benchmarks

Seed 2.1 Pro outperforms in 1 benchmarks (MMMU-Pro), while GPT-5.6 Terra is better at 6 benchmarks (Agents' Last Exam, BrowseComp, DeepSWE, SWE-Bench Pro, Terminal-Bench 2.1, Toolathlon).

GPT-5.6 Terra significantly outperforms across most benchmarks.

Fri Jul 17 2026 • llm-stats.com

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only GPT-5.6 Terra specifies input context (1,050,000 tokens). Only GPT-5.6 Terra specifies output context (128,000 tokens).

ByteDance
Seed 2.1 Pro
Input- tokens
Output- tokens
OpenAI
GPT-5.6 Terra
Input1,050,000 tokens
Output128,000 tokens
Fri Jul 17 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Seed 2.1 Pro and GPT-5.6 Terra support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Seed 2.1 Pro

Text
Images
Audio
Video

GPT-5.6 Terra

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

Seed 2.1 Pro

Proprietary

Closed source

GPT-5.6 Terra

Proprietary

Closed source

Release Timeline

When each model was launched

Seed 2.1 Pro was released on 2026-06-24, while GPT-5.6 Terra was released on 2026-07-09.

GPT-5.6 Terra is 1 month newer than Seed 2.1 Pro.

Seed 2.1 Pro

Jun 24, 2026

3 weeks ago

GPT-5.6 Terra

Jul 9, 2026

1 weeks ago

2w newer

Knowledge Cutoff

When training data ends

GPT-5.6 Terra has a documented knowledge cutoff of 2026-02-16, while Seed 2.1 Pro's cutoff date is not specified.

We can confirm GPT-5.6 Terra's training data extends to 2026-02-16, but cannot make a direct comparison without Seed 2.1 Pro's cutoff date.

Seed 2.1 Pro

—

GPT-5.6 Terra

Feb 2026

Outputs Comparison

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Key Takeaways

ByteDance
Higher MMMU-Pro score (82.7% vs 80.7%)
OpenAI
Larger context window (1,050,000 tokens)
Higher Agents' Last Exam score (50.4% vs 41.4%)
Higher BrowseComp score (87.5% vs 86.2%)
Higher DeepSWE score (69.6% vs 32.7%)
Higher SWE-Bench Pro score (63.4% vs 57.5%)
Higher Terminal-Bench 2.1 score (87.4% vs 71.0%)
Higher Toolathlon score (53.1% vs 50.6%)

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Seed 2.1 Pro and GPT-5.6 Terra side-by-side, then vote on the output you prefer.

Seed 2.1 Pro
✓ Preferred
GPT-5.6 Terra
Open in Playground
AI Model Comparison Table
Feature
ByteDance
Seed 2.1 Pro
OpenAI
GPT-5.6 Terra

FAQ

Common questions about Seed 2.1 Pro vs GPT-5.6 Terra.

Which is better, Seed 2.1 Pro or GPT-5.6 Terra?

GPT-5.6 Terra significantly outperforms across most benchmarks. Seed 2.1 Pro is made by ByteDance and GPT-5.6 Terra is made by OpenAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Seed 2.1 Pro compare to GPT-5.6 Terra in benchmarks?

Seed 2.1 Pro scores CharXiv-D: 95.5%, MathVision: 94.5%, MathVista: 90.7%, MathVerse: 89.7%, Video-MME: 89.2%. GPT-5.6 Terra scores Connectors: 100.0%, HealthBench Consensus: 95.1%, Search and Function-Calling: 94.6%, GPQA: 92.9%, Capture-the-Flag Challenges (Internal): 91.8%.

What are the context window sizes for Seed 2.1 Pro and GPT-5.6 Terra?

Seed 2.1 Pro supports an unknown number of tokens and GPT-5.6 Terra supports 1.1M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

Who makes Seed 2.1 Pro and GPT-5.6 Terra?

Seed 2.1 Pro is developed by ByteDance and GPT-5.6 Terra is developed by OpenAI.

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