Copilot vs Claude: Which One a Microsoft 365 Company Needs, and When to Run Both

What each one actually is

The comparison gets muddled because both names cover several products. For a company on Microsoft 365, the two things worth comparing are these.

Microsoft 365 Copilot is an add-on licence that puts an assistant inside Word, Excel, PowerPoint, Outlook and Teams, plus a chat window. Its defining feature is that it can see what you can see in Microsoft 365: your mailbox, your calendar, the Teams chats you are in and the SharePoint and OneDrive files you have access to. Ask it to summarise the thread with a supplier or draft a reply based on last week’s meeting and it can, because it already sits where that material lives. There is also a free Copilot Chat for work accounts, which is a capable chat assistant but without most of that access to your own content.

Claude is Anthropic’s assistant, bought for a company on the Team or Enterprise plan. It lives in its own app and browser tab. Out of the box it knows nothing about your company; you give it context through shared projects (a team’s instructions, templates and reference files) and through connectors that let it read from other systems. One of those connectors is Microsoft 365 itself, so Claude can search SharePoint, OneDrive, Outlook and Teams once an administrator has approved it in Microsoft Entra. Claude also has add-ins that work inside Excel, PowerPoint and Word.

So the honest starting point is that both can reach your Microsoft content and both can work inside Office files. The difference is where each one is at home. Copilot starts from Microsoft 365 and stays close to it. Claude starts from the task and pulls in whatever the task needs, Microsoft or not. Our guide to AI tools for business covers the wider field if you are still deciding which category of tool you need at all.

Where each one is stronger

Vendors on both sides publish feature grids, and they change every month. What changes much more slowly is which kind of work suits which tool. This is the pattern we see in Nordic and UK companies once both have been used for a few weeks on real work.

Two concrete examples. A 60-person engineering consultancy in Gothenburg moved its project managers to Copilot because their day is Outlook and Teams, and having the weekly status summary appear where they already work beat anything else. The same firm gave Claude to its eight bid writers, who spend days on a single tender response and need a tool that holds the tender documents, the firm’s reference cases and the house style in one project. Nobody had to argue about which tool was better. They were doing different jobs.

A 120-person accountancy practice in the north of England went the other way. Most of its work happens in its practice management and accounting software, not in Microsoft 365, so Copilot’s main strength mattered less. Claude, connected read-only to the systems the teams actually use, covered more of the day.

Claude inside Copilot: the overlap that confuses people

Since late 2025, Microsoft has added Anthropic’s Claude models to Microsoft 365 Copilot alongside OpenAI’s. In parts of Copilot (the Researcher agent, agent mode in Excel and PowerPoint, Copilot Studio and Copilot Cowork among them) the answer you get may come from a Claude model. So “Copilot or Claude” is no longer a choice between two different AI engines. It is a choice between two products.

That distinction matters more than it sounds. Choosing Copilot gives you Claude’s models where Microsoft has chosen to use them, wrapped in Microsoft’s interface, controls and features. It does not give you Claude’s own product: its projects, skills, connectors to non-Microsoft systems, or the way it handles long documents in one conversation. Equally, choosing Claude does not give you Copilot’s place in the Outlook sidebar.

The same data question applies to Claude bought directly. On Team and Enterprise plans, Anthropic does not train its models on your content, and we have written a direct answer to whether Claude is safe for confidential data. Whichever route you take, the decision about which data goes where should be made once, by someone with authority, and written down.

When to run both

Running two assistants is common and often sensible. It is also where most of the waste happens, because companies drift into it rather than choose it. Someone buys Copilot licences as part of the Microsoft agreement, a team starts paying for Claude on a card, and a year later nobody can say who uses what for which work.

Running both makes sense when all three of these are true:

• There are clearly different kinds of work. A large group whose day is email, meetings and quick documents, and a smaller group whose work is long-form writing, analysis or work across non-Microsoft systems.
• Each tool has a named group and a named purpose. “Everyone has Copilot for Microsoft 365 work; the bid, legal and analysis teams also have Claude for deep work” is a policy. “Use whatever you like” is not.
• Someone owns both. One person decides who gets which licence, keeps one set of rules on data, and looks at whether each tool is actually used.

If any of those is missing, pick one tool for now and add the second later for a specific team with a specific reason. A single assistant used properly by the whole company beats two used casually by a few enthusiasts every time.

One more cost of running both that rarely gets counted: connections. If Copilot and Claude each need access to your CRM, your file store and your project tool, that is two sets of permissions to set up, review and switch off when someone leaves. Past a handful of tools, companies start routing both assistants through one controlled entry point. That is what an MCP gateway is for.

Five questions that decide it

If you only have time for one meeting on this, answer these five. Most companies find the answer is obvious by the third.

The fifth question is the one most often skipped, and it decides adoption more than any feature. If a large part of your team already uses a strong assistant privately, rolling out something they consider weaker will push them back to their own accounts, with your data. Asking is cheaper than finding out from expense claims.

What the choice means for your rollout

The tool decision gets far more attention than it deserves. The work that decides whether AI gets used is almost the same whichever assistant you pick, and it is the part most companies skip.

With either tool you need one page of rules on data, written before the first login. You need shared context for each team, so that answers sound like your company and not like a generic template. In Copilot that means curating which SharePoint sites and files it draws on; in Claude it means a shared project per team. You need one connection to the system each team spends most time in. And you need hands-on time on real tasks, because a tool people have only seen in a demo stays unused.

There are differences in the detail. A Copilot rollout often starts with a permissions clean-up, because Copilot will happily surface any file a person technically has access to, including the salary spreadsheet someone shared with the whole company in 2019. A Claude rollout starts with fewer surprises of that kind but needs more effort on context, because Claude only knows what you give it. If you go with Claude, our Claude Team plan rollout guide has the setup and a thirty-day plan. Much of that plan carries over to Copilot too.

Whichever you choose, decide in advance how you will tell whether it worked. Licences assigned is not a measure of anything. Weekly active use by team, and a handful of named tasks that now take less time, are. Our guide to measuring AI adoption covers which numbers to track and how to get them for both tools.

A two-week test that settles it

If the five questions leave you undecided, stop debating and test. Both vendors offer ways to try the business versions, and two weeks on real work tells you more than any comparison article, including this one.

The results are usually less dramatic than the debate before them. One tool tends to win clearly for one group and lose clearly for another, and the right answer follows from who does most of which work. What matters more than the verdict is that the people in the test become the first users who show colleagues how it is done, in whichever tool you pick.

Choosing the tool is the short part. Getting a whole team using it on real work is what we do in a Deployed Kickstart, and keeping it going is Deployed Partner.

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