Model Comparison

DiffusionGemma 26B-A4B vs GPT-5.6 LunaWhich is better in 2026?

GPT-5.6 Luna significantly outperforms across most benchmarks.

Verdict: DiffusionGemma 26B-A4B vs GPT-5.6 Luna — which is better?

DiffusionGemma 26B-A4B (by Google) and GPT-5.6 Luna (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.

DiffusionGemma 26B-A4B outperforms in 0 benchmarks, while GPT-5.6 Luna is better at 2 benchmarks (GPQA, MMMU-Pro). GPT-5.6 Luna significantly outperforms across most benchmarks.

Choose DiffusionGemma 26B-A4B if…

  • you need open weights you can self-host or fine-tune

Choose GPT-5.6 Luna if…

  • you want the strongest raw capability — it leads on 2 of 2 shared benchmarks
  • you want the most recent training data — it shipped Jul 2026

Performance Benchmarks

Comparative analysis across standard metrics

2 benchmarks

DiffusionGemma 26B-A4B outperforms in 0 benchmarks, while GPT-5.6 Luna is better at 2 benchmarks (GPQA, MMMU-Pro).

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

Google
DiffusionGemma 26B-A4B
Input- tokens
Output- tokens
OpenAI
GPT-5.6 Luna
Input1,050,000 tokens
Output128,000 tokens
Fri Jul 17 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both DiffusionGemma 26B-A4B and GPT-5.6 Luna support multimodal inputs.

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

DiffusionGemma 26B-A4B

Text
Images
Audio
Video

GPT-5.6 Luna

Text
Images
Audio
Video

License

Usage and distribution terms

DiffusionGemma 26B-A4B is licensed under Apache 2.0, while GPT-5.6 Luna uses a proprietary license.

License differences may affect how you can use these models in commercial or open-source projects.

DiffusionGemma 26B-A4B

Apache 2.0

Open weights

GPT-5.6 Luna

Proprietary

Closed source

Release Timeline

When each model was launched

DiffusionGemma 26B-A4B was released on 2026-06-10, while GPT-5.6 Luna was released on 2026-07-09.

GPT-5.6 Luna is 1 month newer than DiffusionGemma 26B-A4B.

DiffusionGemma 26B-A4B

Jun 10, 2026

1 months ago

GPT-5.6 Luna

Jul 9, 2026

1 weeks ago

4w newer

Knowledge Cutoff

When training data ends

DiffusionGemma 26B-A4B has a knowledge cutoff of 2025-01-01, while GPT-5.6 Luna has a cutoff of 2026-02-16.

GPT-5.6 Luna has more recent training data (up to 2026-02-16), making it potentially better informed about events through that date compared to DiffusionGemma 26B-A4B (2025-01-01).

DiffusionGemma 26B-A4B

Jan 2025

GPT-5.6 Luna

Feb 2026

1.1 yr newer

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

Google
Has open weights
OpenAI
Larger context window (1,050,000 tokens)
Higher GPQA score (92.3% vs 73.2%)
Higher MMMU-Pro score (78.4% vs 54.3%)

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against DiffusionGemma 26B-A4B and GPT-5.6 Luna side-by-side, then vote on the output you prefer.

DiffusionGemma 26B-A4B
✓ Preferred
GPT-5.6 Luna
Open in Playground
AI Model Comparison Table
Feature
Google
DiffusionGemma 26B-A4B
OpenAI
GPT-5.6 Luna

FAQ

Common questions about DiffusionGemma 26B-A4B vs GPT-5.6 Luna.

Which is better, DiffusionGemma 26B-A4B or GPT-5.6 Luna?

GPT-5.6 Luna significantly outperforms across most benchmarks. DiffusionGemma 26B-A4B is made by Google and GPT-5.6 Luna is made by OpenAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does DiffusionGemma 26B-A4B compare to GPT-5.6 Luna in benchmarks?

DiffusionGemma 26B-A4B scores MMMLU: 81.5%, MMLU-Pro: 77.6%, GPQA: 73.2%, MathVision: 70.5%, AIME 2026: 69.1%. GPT-5.6 Luna scores Connectors: 99.9%, HealthBench Consensus: 95.1%, GPQA: 92.3%, Search and Function-Calling: 89.7%, Capture-the-Flag Challenges (Internal): 85.2%.

What are the context window sizes for DiffusionGemma 26B-A4B and GPT-5.6 Luna?

DiffusionGemma 26B-A4B supports an unknown number of tokens and GPT-5.6 Luna supports 1.1M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between DiffusionGemma 26B-A4B and GPT-5.6 Luna?

Key differences include licensing (Apache 2.0 vs Proprietary). See the full comparison above for benchmark-by-benchmark results.

Who makes DiffusionGemma 26B-A4B and GPT-5.6 Luna?

DiffusionGemma 26B-A4B is developed by Google and GPT-5.6 Luna is developed by OpenAI.

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