All three do the same basic thing. You write the instructions once, attach the reference files, and everyone gets consistent help with a job they repeat. Below is how they differ, what to do about GPTs you already have, and how we'd pick the first assistant to build.
What each option is
Claude Projects. A Project holds instructions, reference files and its own chat history for one kind of work. Every Claude plan has them (Free is limited to five), and paid plans can hold much larger reference libraries. On Team and Enterprise you can share a Project with specific people or the whole organisation, either view-only or with permission to edit. For a process the whole business follows, Team and Enterprise owners can also add skills that appear for everyone, and plugins bundle skills and connectors for a role or team.
Custom GPTs. A GPT combines instructions, up to 20 knowledge files and optional tools such as web search, data analysis or connections to other systems. Personal accounts (Free, Go, Plus and Pro) can no longer create new GPTs, and only Business, Enterprise and Edu workspaces can. All of them are scheduled to retire on 11 December 2026, or 11 February 2027 for Enterprise workspaces with an approved deferral.
ChatGPT plugins and workspace agents. Plugins are OpenAI's replacement for GPTs and package instructions, reference files and app connections together. On Business and Enterprise, workspace agents go further. They connect to the apps your team uses, can run on a schedule or inside a Slack channel, and ask for approval before write actions by default.
Microsoft Copilot agents. Microsoft has two builders. Agent Builder, inside the Microsoft 365 Copilot app, is for quick question-and-answer agents for a person or small team, grounded in your SharePoint files or email, and it respects each person's existing permissions. Copilot Studio is a separate portal for agents used across a department or with customers, with workflows, approvals and connections beyond Microsoft 365.
Side by side
| Claude Project | ChatGPT workspace agent | Copilot Agent Builder | |
|---|---|---|---|
| Best first job | One job with set instructions and reference documents | A repeat workflow that uses connected apps | Answering questions from your SharePoint files or email |
| Plan you need | Any Claude plan; sharing needs Team or Enterprise | ChatGPT Business or Enterprise | A Microsoft 365 Copilot licence for agents that use your SharePoint files or email. Free for web-only agents |
| Sharing | Named people or the whole organisation, view or edit | Private, by link, in the workspace directory, or with named people or groups | Shared within your organisation, under admin settings |
| Runs on a schedule | Not on its own; Claude Cowork has scheduled tasks | Yes, or from Slack | Agent Builder is for lightweight Q&A; workflows need Copilot Studio |
| Watch out for | Keep reference files current | Connections set up on the builder's account let others act with that access | SharePoint knowledge needs a Copilot licence for each user |
If you already have custom GPTs
Don't wait until December. OpenAI's migration FAQ sets out the steps and the catches:
- List the GPTs your team relies on and who built each one. Only the creator (or an admin, on Enterprise) can migrate it.
- Finish and publish any edits first. Migration uses the latest published version, so drafts don't transfer (publishing a GPT doesn't mean sharing it publicly). The original GPT becomes read-only afterwards.
- Migrate from My GPTs when the option appears. The instructions become a skill, knowledge files become reference files, and connected apps are added as apps. The GPT's chosen model doesn't carry over.
- Rebuild anything that used custom actions. Those don't transfer, so any GPT that connected to your own systems needs a new connection.
- Test with familiar prompts and at least one hard case before telling people to switch. The new plugin starts private, so share it on purpose.
Existing conversations with GPTs stay accessible after retirement. On Enterprise, OpenAI plans to stop the creation of new GPTs on 26 October 2026, so publish any drafts you want to migrate before then.
If you're moving to Claude instead, there's no import. Copy the GPT's instructions into a new Project, upload the same files, and run the same test prompts. If you're staying on ChatGPT and still working out which plan you need, our guide to ChatGPT Business vs Plus vs Enterprise covers it in Australian dollars.
Which assistant to build first
Build on the tool your team already uses. An assistant in a tool people don't open won't get used, however good it is. If you're still choosing the tool, our Claude vs ChatGPT vs Copilot comparison is the place to start.
Pick a job that comes round every week and has a clear right answer. Good first assistants we see work:
- A quote or proposal drafter that uses your price list and three past examples.
- A "how do we do this here?" helper that answers from your procedures and policies.
- A customer reply drafter that writes in your tone.
- An onboarding helper new starters can ask instead of interrupting the busiest person in the office.
Leave anything that sends, posts or changes records for later. Start with assistants that draft and answer, and add actions once people trust the output.
Here's a set of instructions we'd start from on any of the three:
Role: You help our [team] with [one job, e.g. drafting quotes for residential jobs].
Use these files: [price list], [three past quotes we were happy with], [our terms and conditions].
Always: write in plain Australian English, use prices only from the price list, and list any assumptions at the end.
Never: invent prices, discounts or dates. If information is missing, ask for it.
Output: [the format you want, e.g. a one-paragraph summary, then line items, then terms].Give every assistant an owner. One person keeps the files current, tests changes and decides who can edit. When your prices or policies change, the assistant changes the same week.
Where team assistants go wrong
- Too broad. An assistant for "anything to do with clients" gives vague answers. One job per assistant works better.
- Built in someone's personal account. When that person leaves, or when GPTs retire, the assistant goes with them. Build in the business workspace from day one.
- Out-of-date files. An assistant quoting last year's price list does more harm than having none.
- Nobody checking the output. Treat early answers like a new starter's work and review them until you trust the pattern.
- Measuring logins. Ask people to show you what the assistant saved them this week, and share the good examples with the team.
Common questions
A version of ChatGPT set up for one job, with its own instructions and files. OpenAI is retiring them on 11 December 2026 and moving them to plugins.
No. Personal accounts, including Plus and Pro, can't create new GPTs. Business, Enterprise and Edu workspaces still can for now, though Enterprise creation is planned to stop on 26 October 2026.
OpenAI says existing conversations remain accessible. The GPTs themselves and their pages become inaccessible.
Free accounts can create up to five Projects. Sharing a Project with your team needs a Team or Enterprise plan.
Agents grounded only in web content can be built for free. Microsoft says agents that use SharePoint or OneDrive content need the signed-in person to have a Microsoft 365 Copilot licence, and email and Teams content needs a licence too. Without a Copilot licence, Microsoft offers Copilot Credits or pay-as-you-go billing to use Agent Builder and Copilot Studio.