Four differences worth caring about.
Strip out the noise. For a specialist firm of five to fifty people, four things separate Claude set up properly, with rules about your data, from a chat window anyone can sign up to.
A workspace, not a chat window.
Claude can work directly on the folders on your machine. ChatGPT's access to your local files is more constrained.
Why it mattersYour work lives in files and folders, not in a chat box. A tool that operates where the work already sits saves you the copy-and-paste tax on every job.
Automation that does the work, not a reminder that you should.
ChatGPT's scheduled Tasks are limited. They don't support file uploads, and they don't run your custom GPTs. Claude's scheduled tasks fire a full working session with access to your files and tools.
Why it mattersOne sends you a nudge. The other actually produces the report, the draft or the check while you're asleep.
Projects that scale past the window.
Claude Projects take files up to 30MB each, with no limit on how many. When your project knowledge grows past what the model can hold at once, it automatically pulls in the right parts, expanding your usable capacity by up to around ten times, at no extra cost.
Why it mattersYour firm's standards, past jobs and templates can sit behind the model without you trimming them down to fit.
Data governance you can point to.
On the paid business plan you get it in writing: they do not train on your data, they say how long they keep it, and they say what the model may and may not hold on to.
Why it mattersWhen a client or an acquirer asks "where does our data go?", you have an answer on paper, not a shrug.
The ChatGPT claims above (§01, §02) checked against OpenAI's own documentation and release notes, 31 July 2026. Both products ship fast; treat this as a snapshot, not a permanent scorecard.
Weighing this up for your own firm? We'll tell you straight where you stand and what's worth doing first.
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