GPT-5.1 vs Gemini 1.5 Pro

1. Configurable Reasoning for Agentic Tasks

• Built to excel in autonomous or semi-autonomous coding workflows, with adjustable reasoning effort for planning, refactoring and debugging.

2. Fast Multi-Modal Input with Large Output

• Accepts both text and image inputs while producing text outputs.
• Offers up to 128 k output tokens, allowing long responses and code generation across multiple files.

3. Large Context & Knowledge Cut-Off

• 400 k token context window supports processing large codebases or documents.
• Knowledge cut-off of Sep 30 2024 ensures familiarity with recent tools and frameworks.

4. Reasoning Token Support

• Provides explicit support for reasoning tokens, enabling developers to fine-tune the balance between reasoning depth and speed.

1. Breakthrough long-context window up to 1,000,000 tokens

• Can process 1 hour of video, 11 hours of audio, 700k+ words, or 100k+ lines of code in a single prompt.
• Supports advanced retrieval, reasoning, summarization, and cross-document tasks.
• Achieves 99% retrieval accuracy on 1M-token Needle-In-A-Haystack tests.

2. Strong multimodal reasoning across video, audio, images, and text

• Can analyze long videos (e.g., full silent films), track events, infer causality, and identify small details.
• Handles large complex documents like manuals, transcripts, and books.

3. High-performance reasoning and problem solving

• Comparable to Gemini 1.0 Ultra across many benchmarks.
• Excels at code reasoning, multi-step explanations, and large-scale codebase analysis.

4. Advanced code understanding and generation

• Performs problem-solving on codebases exceeding 100,000 lines.
• Capable of cross-file reasoning, debugging guidance, API comprehension, and generating structured code improvements.

5. Efficient Mixture-of-Experts (MoE) architecture

• Activates only relevant expert pathways per input.
• Enables faster training, lower latency, and more efficient serving.
• Dramatically improves scalability and inference speed.

6. Exceptional in-context learning capabilities

• Learns new tasks directly from long prompts without fine-tuning.
• Demonstrated by learning to translate a low-resource language (Kalamang) from a grammar manual.

7. High-fidelity multimodal understanding

• Reads, analyzes, and reasons about long PDFs, code repositories, images, and videos together.
• Enables new classes of applications: legal analysis, scientific review, codebase audits, long-form content generation, etc.

8. Safety and reliability first

• Undergoes extensive ethics, safety testing, and red-teaming.
• Improved representational safety and reduced hallucinations compared to previous generations.

9. Available for developers and enterprises

• Accessible via AI Studio and Vertex AI.
• Supports future pricing tiers for expanded context windows.
• Designed for real enterprise-scale workloads.

10. Widely capable mid-size model

• Positioned between Gemini Pro and Gemini Ultra generations.
• Well-balanced: reasoning, multimodality, long-context, and speed.