Nano Banana Pro vs GPT-5.1: Which AI Image Model Wins in 2025? (Benchmarks & Review)

Most AI image model comparisons online feel like hype, marketing, or cherry-picked examples. I wanted something more practical.

For this test, I ran the exact same prompts through both GPT-5.1 (ChatGPT's latest image generation model) and Nano Banana Pro using scenarios that real creators actually care about: realistic portraits, stylized anime characters, and clean branded graphics.

These represent the three big categories people use AI visuals for every day: content, characters, and communication. The goal isn't to declare a universal winner, but to show their strengths side-by-side so you know which model fits your workflow.

Below are the results of my 2025 benchmarks for Nano Banana Pro vs. GPT-5.1.

Test Methodology

To keep the comparison fair, both models received the exact same text prompts. I tested three distinct categories:

• Prompt 1: Realistic Portrait (Photography)
• Prompt 2: Anime Cyberpunk Character (Stylization)
• Prompt 3: Clean Branded OG-Card Graphic (Design)

Prompt 1: Realistic Portrait Performance

The Prompt: A realistic studio portrait of a person with soft diffused lighting, sharp eyes, natural skin texture, and balanced facial proportions. Neutral beige backdrop, subtle depth of field, no stylization, no filters, no makeup, no exaggerated features. Clean professional photography style.

Verdict: Tie (Best for General Stock Photos)

Both GPT-5.1 and Nano Banana Pro delivered natural, realistic portraits with accurate lighting and clean skin texture. If you need stock-style photos, website visuals, or general b-roll imagery, either model is strong enough to use interchangeably.

• Nano Banana Pro: Excellent skin texture and lighting accuracy.
• GPT-5.1: Reliable facial proportions and eye sharpness.

Prompt 2: Anime Cyberpunk Character

The Prompt: Anime-style cyberpunk character standing in a neon-lit alley at night. Dynamic pose, glowing signs in the background, cool and warm light reflections, detailed outfit with tech accessories, expressive anime eyes, bold outlines, and vibrant colors. Clean composition with strong atmosphere.

Verdict: Winner — Nano Banana Pro

Both models produced good-looking anime characters, but the differences become clear once you zoom into the details. Nano Banana Pro captured the specific "genre" feel much better than GPT-5.1.

Why Nano Banana Pro Won:

• Genre Accuracy: Nailed the cyberpunk aesthetic with goggles, tech wear, and neon gear.
• Dynamic Posing: Captured a more expressive, action-oriented pose.
• Style Match: The style feels closer to Cyberpunk 2077 or 90s anime, adhering strictly to the prompt's requested atmosphere.

Where GPT-5.1 Struggled:

• Too Polished: The output looked like a modern animated TV series—smooth, but missing the "gritty" texture requested.
• Static Poses: The character felt stiff compared to Nano Banana's dynamic composition.

Prompt 3: Clean OG-Card Branding Graphic

The Prompt: A clean, minimalist OG-card style graphic with a modern tech aesthetic. Neutral beige and charcoal tones, soft subtle shadows, simple rectangular layout. Include clear, legible text that reads: "AI Model Comparison 2025". Balanced spacing, crisp typography, no distortion, no extra decorations. Professional editorial design.

Verdict: Winner — Nano Banana Pro

This result was the biggest surprise of the benchmark. GPT-5.1 struggled to create a compelling layout, whereas Nano Banana Pro produced a near-publishable asset.

Why Nano Banana Pro Won:

• Design Hierarchy: Created an infographic-style composition with proper structure and spacing.
• Professional Polish: The output looked like a designed slide rather than a random generation.

Where GPT-5.1 Struggled:

• Too Simple: It followed the "minimal" instruction too literally, resulting in a plain, uninspired image.
• Lack of Structure: It didn't attempt to organize the information visually.

Final Conclusion: Which Model is Better?

Both models are excellent, but they shine in different areas. For most users in 2025, the best choice depends on your specific output needs.

The Bottom Line:

If you want infographics, slides, or stylistically accurate illustrations, Nano Banana Pro has the clear advantage. If you want clean characters or straightforward compositions, GPT-5.1 remains extremely dependable.

I will continue testing both models with deeper prompts in future updates.

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