What is the difference between GPT-4.5 and GPT-5.1 Codex Max?

Both are developed by OpenAI but target different use cases. You can compare their actual outputs across 25 challenges on Rival to see how they differ in practice.

Which is better, GPT-4.5 or GPT-5.1 Codex Max?

It depends on your use case. GPT-4.5 and GPT-5.1 Codex Max each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 25 challenges so you can judge which fits your needs best.

How can I compare GPT-4.5 and GPT-5.1 Codex Max on Rival?

This page shows a side-by-side comparison of GPT-4.5 and GPT-5.1 Codex Max across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

What is the difference between GPT-4.5 and GPT-5.1 Codex Max?

Both are developed by OpenAI but target different use cases. You can compare their actual outputs across 25 challenges on Rival to see how they differ in practice.

Which is better, GPT-4.5 or GPT-5.1 Codex Max?

It depends on your use case. GPT-4.5 and GPT-5.1 Codex Max each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 25 challenges so you can judge which fits your needs best.

How can I compare GPT-4.5 and GPT-5.1 Codex Max on Rival?

This page shows a side-by-side comparison of GPT-4.5 and GPT-5.1 Codex Max across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

GPT-4.5 vs GPT-5.1 Codex Max: Which Is Better?

Updated Dec 2025

Our Verdict

GPT-4.5

GPT-5.1 Codex Max

No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.

Too close to call

API pricing

Cost per 1M tokens

GPT-4.5

Input

$75.00

Output

$150.00

GPT-5.1 Codex Max

Input

—

Output

—

Writing DNA

Style Comparison

Similarity

44%

GPT-4.5 uses 20.5x more transitions

GPT-4.5

GPT-5.1 Codex Max

63%Vocabulary60%

16wSentence Length16w

0.57Hedging0.36

4.7Bold2.3

6.4Lists4.2

0.00Emoji0.00

1.30Headings0.12

0.54Transitions0.03

Based on 11 + 13 text responses

Research

What we learned reading every model

GPT-4.5 and GPT-5.1 Codex Max have opinions about your brand too.Ask 10 models what they tell people about you. Verbatim receipts.Run the mirror

FAQ

Common questions

Keep exploring

More comparisons

GPT-4.5 vs Llama 4 MaverickNew provider

GPT-5.1 Codex Max vs GPT-5Same lab

GPT-4.5 vs MiniMax M3New provider

Updated Dec 2025

Our Verdict

GPT-4.5

GPT-5.1 Codex Max

No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.

Too close to call

API pricing

Cost per 1M tokens

GPT-4.5

Input

$75.00

Output

$150.00

GPT-5.1 Codex Max

Input

—

Output

—

Writing DNA

Style Comparison

Similarity

44%

GPT-4.5 uses 20.5x more transitions

GPT-4.5

GPT-5.1 Codex Max

63%Vocabulary60%

16wSentence Length16w

0.57Hedging0.36

4.7Bold2.3

6.4Lists4.2

0.00Emoji0.00

1.30Headings0.12

0.54Transitions0.03

Based on 11 + 13 text responses

Research

What we learned reading every model

GPT-4.5 and GPT-5.1 Codex Max have opinions about your brand too.Ask 10 models what they tell people about you. Verbatim receipts.Run the mirror

FAQ

Common questions

Keep exploring

More comparisons

GPT-4.5 vs Llama 4 MaverickNew provider

GPT-5.1 Codex Max vs GPT-5Same lab

GPT-4.5 vs MiniMax M3New provider