GPT-4.1 Nano vs GPT-5 Codex

Compare GPT-4.1 Nano and GPT-5 Codex, both from OpenAI, tested across 37 shared challenges. Updated April 2026.

Which is better, GPT-4.1 Nano or GPT-5 Codex?

GPT-4.1 Nano and GPT-5 Codex are both competitive models. Compare their real outputs side by side below.

Key Differences Between GPT-4.1 Nano and GPT-5 Codex

GPT-4.1 Nano is made by openai while GPT-5 Codex is from openai.

Our Verdict
GPT-5 Codex
GPT-5 Codex
GPT-4.1 Nano
GPT-4.1 NanoRunner-up

No community votes yet. On paper, GPT-5 Codex has the edge — bigger model tier, newer.

Too close to call
Writing DNA

Style Comparison

Similarity
93%

GPT-5 Codex uses 14.6x more emoji

GPT-4.1 Nano
GPT-5 Codex
57%Vocabulary64%
25wSentence Length17w
0.72Hedging0.38
5.6Bold2.3
4.9Lists3.5
0.00Emoji0.15
0.71Headings0.49
0.22Transitions0.05
Based on 24 + 13 text responses
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GPT-4.1 NanoGPT-5 Codex

279 AI models invented the same fake scientist.

We read every word. 250 models. 2.14 million words. This is what we found.

AI Hallucination Index 2026
Free preview13 of 58 slides
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