Two different starting points
Microsoft 365 Copilot lives inside the apps your staff already use. It can draft in Word, summarise an Outlook thread, create slides from a document, analyse data in Excel and recap a Teams meeting. Its distinguishing feature is that it can search and draw on the emails, chats, files and meetings a person already has permission to see, so it can answer questions about your own business.
ChatGPT began as a standalone assistant. You open it, ask questions, paste or upload information and get answers, drafts or analysis. Business plans add workspace administration, sharing among colleagues and data commitments for business use, and the product continues to add connections to other services. Its strength is breadth, covering writing, reasoning, coding, images and research in one place.
How each handles company data
Microsoft states that Copilot for business works within your Microsoft 365 tenant's existing security and permissions, and that prompts and responses from organisational accounts are not used to train its foundation models. Because it can reach everything a user can access, any oversharing in SharePoint or Teams becomes visible through Copilot. That makes tidying permissions a prerequisite.
OpenAI states that business and enterprise plans do not use your workspace's data to train its models by default, and offers admin controls over the workspace. Data reaches ChatGPT when staff paste, upload or connect it, so the question is what people choose to share. With free personal accounts, different terms apply, which is the main reason to provide a business plan rather than let staff use personal ones. Check both vendors' current terms rather than relying on any summary, because they change.
Where Copilot tends to fit
Copilot suits organisations that already live in Microsoft 365 and want help inside familiar tools: catching up on long email chains, preparing for meetings from related documents, getting Teams meeting summaries and finding information spread across SharePoint and OneDrive. Staff do not need to copy information between windows, which lowers the risk of pasting sensitive data into the wrong place.
It needs a suitable Microsoft 365 plan and a separate Copilot licence for full features, plus some preparation: permissions reviewed, files organised, and staff shown how to prompt it well. Microsoft also offers a free Copilot chat experience for work accounts with fewer features; check what is included in your current licensing.
Where ChatGPT tends to fit
ChatGPT suits people whose work involves a lot of open-ended thinking, writing and analysis that is not tied to company files: marketing drafts, research, brainstorming, explaining technical topics, working through data that has been exported, or writing scripts and formulas. It is also platform-neutral, which matters for businesses on Google Workspace or mixed systems. Because it is separate from your files by default, it is less likely to surface something it should not, but more dependent on staff judgement about what to paste. A clear AI use policy matters more in that setting.
How to decide
Run a short, structured trial. Pick five or six real tasks from different roles, such as summarising a client email thread, drafting a proposal section or analysing a monthly sales export, and have a small group try them in each tool for a few weeks. Record time saved, quality and frustrations. Include the admin view as well as the user view: how licences, data settings and offboarding are handled.
Consider who actually needs what. A business might give Copilot to managers and administrators who live in Outlook and Teams, and ChatGPT business seats to the marketing person, or settle on just one. There is no prize for buying everything, and unused AI licences are an easy way to add cost.
Whichever you choose
Use business accounts tied to company sign-in, never personal ones for company data. Write a short use policy, train people on prompting and checking output, and review usage after a few months. Both products change quickly, so revisit the choice yearly. Prices also change, so check current pricing with Microsoft and OpenAI or your reseller before budgeting, rather than relying on figures from articles.
Plan for change as well. Features that are exclusive to one product this year often appear in the other the next, and both vendors regularly rename plans and move capabilities between tiers. Avoid long commitments for large numbers of seats until usage settles, and make sure whoever manages your licences knows which staff actually use their AI seat each month, so idle licences can be reassigned or released.
In short
- Copilot works inside Microsoft 365 and can use the files and email each user can access.
- ChatGPT is a flexible standalone assistant that works with what staff give it.
- Copilot exposes oversharing; ChatGPT relies on staff judgement about pasting data.
- Trial both on real tasks, use business accounts only and review yearly.