Chat with all AIClaude Sonnet 5.5 vs GPT-6.1 Terra
Claude Sonnet 5.5 (Anthropic) and GPT-6.1 Terra (OpenAI) are both in Chat with all AI's model menu. Here's how they differ in practice, which to pick for which task, and how to compare them on your own prompt in seconds.
At a glance
| Claude Sonnet 5.5 | GPT-6.1 Terra | |
|---|---|---|
| Made by | Anthropic | OpenAI |
| Group in the menu | Complex work | Complex work |
| Speed | Fast | Fast |
| Best for | Writing that needs the right tone, Coding and code review | Drafting longer emails and documents, Analyzing a page or report |
| On Pro | Unlimited (fair use) | Unlimited (fair use) |
| Separate subscription needed? | No — included | No — included |
Quick verdict
- Coding: Both are solid — try your prompt on each.
- Writing: Claude Sonnet 5.5 usually has the edge.
- Speed: Both are solid — try your prompt on each.
- Hard reasoning: Both are solid — try your prompt on each.
- Brainstorming: Claude Sonnet 5.5 usually has the edge.
Verdicts reflect how these models are generally positioned and reported in 2026. Your own prompts are the best test.
Where Claude Sonnet 5.5 shines
- Very natural, human-sounding prose
- Strong, careful code with explanations
- Keeps the author's voice when editing
- Good judgment on what to leave out
Where GPT-6.1 Terra shines
- Good balance of speed and depth
- Clear reasoning you can follow
- Handles multi-part instructions
- Consistent formatting for documents
Watch-outs
Claude Sonnet 5.5
- For the very hardest problems step up to Opus 5.5
- Sometimes cautious — tell it the context and goal
- No live web search inside the extension
GPT-6.1 Terra
- For the hardest reasoning pick Sol or a max-tier model
- Can over-structure casual answers — ask for prose if you prefer
- No browsing: share the page with 'This page' instead
Prompts to test both
Send a prompt with one model, then switch the model and press Regenerate. Each answer is labelled with the model that wrote it.
Bottom line
Choose Claude Sonnet 5.5 for writing that needs the right tone and coding and code review. Choose GPT-6.1 Terra for drafting longer emails and documents and analyzing a page or report. They come from different labs, so using both is a great way to catch mistakes.
Frequently asked questions
Is Claude Sonnet 5.5 better than GPT-6.1 Terra?
It depends on the task. Claude Sonnet 5.5 is strongest at writing that needs the right tone; GPT-6.1 Terra shines at drafting longer emails and documents. The quickest way to know is to ask both the same question — in Chat with all AI that's one model switch.
Which is faster, Claude Sonnet 5.5 or GPT-6.1 Terra?
In practice Claude Sonnet 5.5 is fast and GPT-6.1 Terra is fast. Real speed also depends on answer length and load.
Can I use Claude Sonnet 5.5 and GPT-6.1 Terra with one subscription?
Yes. Both are in Chat with all AI. Try them with 3 free requests; Pro covers both.
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