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

GPT-5.1 Codex Max is developed by OpenAI while xAI: Grok 4.5 is developed by xAI. You can compare their actual outputs across 52 challenges on Rival to see how they differ in practice.

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

It depends on your use case. GPT-5.1 Codex Max and xAI: Grok 4.5 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 52 challenges so you can judge which fits your needs best.

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

This page shows a side-by-side comparison of GPT-5.1 Codex Max and xAI: Grok 4.5 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-5.1 Codex Max and xAI: Grok 4.5?

GPT-5.1 Codex Max is developed by OpenAI while xAI: Grok 4.5 is developed by xAI. You can compare their actual outputs across 52 challenges on Rival to see how they differ in practice.

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

It depends on your use case. GPT-5.1 Codex Max and xAI: Grok 4.5 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 52 challenges so you can judge which fits your needs best.

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

This page shows a side-by-side comparison of GPT-5.1 Codex Max and xAI: Grok 4.5 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-5.1 Codex Max vs xAI: Grok 4.5: Which Is Better?

Updated Jul 2026

Our Verdict

GPT-5.1 Codex Max

xAI: Grok 4.5

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-5.1 Codex Max

Input

—

Output

—

xAI: Grok 4.5

Input

$2.00

Output

$6.00

Writing DNA

Style Comparison

Similarity

64%

xAI: Grok 4.5 uses 9.0x more emoji

GPT-5.1 Codex Max

xAI: Grok 4.5

60%Vocabulary61%

16wSentence Length16w

0.36Hedging0.23

2.3Bold2.5

4.2Lists2.4

0.00Emoji0.09

0.12Headings0.48

0.03Transitions0.06

Based on 13 + 27 text responses

Research

What we learned reading every model

GPT-5.1 Codex Max and xAI: Grok 4.5 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

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GPT-5.1 Codex Max vs Llama 4 MaverickNew provider

GPT-5.1 Codex Max vs Gemini 2.5 Pro (I/O Edition)New provider

Updated Jul 2026

Our Verdict

GPT-5.1 Codex Max

xAI: Grok 4.5

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-5.1 Codex Max

Input

—

Output

—

xAI: Grok 4.5

Input

$2.00

Output

$6.00

Writing DNA

Style Comparison

Similarity

64%

xAI: Grok 4.5 uses 9.0x more emoji

GPT-5.1 Codex Max

xAI: Grok 4.5

60%Vocabulary61%

16wSentence Length16w

0.36Hedging0.23

2.3Bold2.5

4.2Lists2.4

0.00Emoji0.09

0.12Headings0.48

0.03Transitions0.06

Based on 13 + 27 text responses

Research

What we learned reading every model

GPT-5.1 Codex Max and xAI: Grok 4.5 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-5.1 Codex Max vs MiniMax M3New provider

GPT-5.1 Codex Max vs Llama 4 MaverickNew provider

GPT-5.1 Codex Max vs Gemini 2.5 Pro (I/O Edition)New provider