The short answer.
Start from where your people already work. If your organization runs on Microsoft 365 and most knowledge sits in Outlook, Teams and SharePoint, Microsoft Copilot is the natural first candidate, provided your SharePoint permissions are in good shape. If you want one subscription that covers chat, delegated tasks and coding, with custom connectors to your own systems, compare Claude and ChatGPT side by side.
The three are not exclusive. Microsoft offers Anthropic models inside Microsoft Copilot and Copilot Studio, Claude can connect to Microsoft 365 content, and Microsoft Foundry hosts both Anthropic and OpenAI models. Running Microsoft Copilot for everyone and a second assistant for specific teams can work well, as long as each one has an owner and a clear scope.
| Product family | Where it lives | A natural fit when | Check first |
|---|---|---|---|
| Microsoft Copilot | Outlook, Teams, Word, Excel, SharePoint and the Copilot app | Your organization runs on Microsoft 365 and knowledge sits in mail, files and meetings | SharePoint oversharing, Entra ID policies and qualifying Microsoft 365 plans |
| Claude | Claude apps on web, desktop and mobile, plus Claude Code for engineers | You want chat, delegated tasks and coding on one subscription, connected to your systems | Team versus Enterprise controls, the network path for connectors and usage billing on Enterprise |
| ChatGPT | ChatGPT on web, desktop and mobile, plus Codex for engineers | You want a broad workforce assistant with plugins and delegated tasks through ChatGPT Work | Plugin and action controls by role, custom GPT migration and a separate API account |
Reference: Microsoft: Anthropic models in Microsoft Online Services
Compare like with like.
Each vendor sells several products, and comparisons go wrong when a workforce assistant is set against a developer platform. Line the products up by the job they do.
Delegated-task products are the newest and change fastest. Anthropic is merging Claude Cowork into the main Claude app, starting with Pro and Max plans; Team and Enterprise organizations keep the separate Cowork experience for now, and Anthropic says Enterprise admins will get at least 30 days’ notice. Microsoft Copilot Cowork asks the user to approve each action before it happens. ChatGPT Work runs tasks in the cloud or locally through the ChatGPT desktop app.
| Job | Anthropic | OpenAI | Microsoft |
|---|---|---|---|
| Workforce assistant | Claude Team and Claude Enterprise | ChatGPT Business and ChatGPT Enterprise | Microsoft Copilot Chat and Microsoft Copilot |
| Delegated multi-step tasks | Claude Cowork | ChatGPT Work | Microsoft Copilot Cowork |
| Coding | Claude Code | Codex | GitHub Copilot |
| Build your own agents | Claude API, including Claude Managed Agents | OpenAI API: Responses API, Agents SDK, Agents API and Agent Builder | Copilot Studio and Microsoft Foundry |
| Connector and agent controls | Organization connector settings and role-based permissions | Plugin and action controls by workspace role | Agent 365, the Microsoft 365 admin center and Power Platform data policies |
Admin and security controls.
Security reviews usually turn on identity, audit, retention, residency and training on customer data. The table compares the enterprise tiers. Lower tiers have fewer controls: Claude Team has SSO and JIT provisioning but not SCIM, audit logs or the Compliance API, and ChatGPT Business has SAML SSO and MFA without the Enterprise additions.
Microsoft Copilot works differently. It inherits Microsoft 365 permissions, so it only shows content a user can already view. That makes permission hygiene in SharePoint and OneDrive the first security task, before any AI-specific setting.
Mixed estates need extra checks. Claude’s Microsoft 365 connector needs a one-time consent from a Microsoft Entra Global Administrator, and write tools such as sending email only work if an admin enables them. In the other direction, Anthropic models inside Microsoft Copilot are excluded from the EU Data Boundary and are off by default for customers in the EU and UK.
| Control | Claude Enterprise | ChatGPT Enterprise | Microsoft Copilot |
|---|---|---|---|
| Identity | SSO, SCIM and domain capture | SAML SSO, SCIM and domain verification | Microsoft Entra ID, with MFA and Conditional Access |
| Access model | Role-based permissions; each member signs in to connectors | Custom roles by group; plugins and actions enabled by role | Only content the user can already view |
| Audit | Audit logs and the Compliance API | Compliance API for audit records | Microsoft Purview audit and DSPM for AI |
| Retention | Custom periods, 30 days minimum | Data retention controls | Purview retention policies |
| Residency | US-only inference option | Data residency controls | Product Terms commitments and the EU Data Boundary |
| Training on your data | Not used by default | Not used by default | Not used to train foundation models |
| Other controls | IP allowlisting, Tenant Restrictions and customer-managed keys | EKM and managed configuration for desktop clients | Sensitivity labels, DLP and Restricted Content Discovery |
Connecting business systems: connectors and MCP.
All three can use the Model Context Protocol (MCP) to reach tools outside the product. In principle one remote MCP server can serve all of them, but the clients differ in where their calls come from, how they authenticate and which MCP features they use. Claude supports MCP tools, prompts and resources, while Copilot Studio supports tools and resources. Test each client against the same server before you promise one integration for everyone.
The network path is the question most teams miss. Claude’s remote connectors are called from Anthropic’s cloud, so a private server must allowlist Anthropic’s IP ranges. ChatGPT can reach a private server through OpenAI’s Secure MCP Tunnel, which only makes outbound calls from your network. Copilot Studio connects through Power Platform connectors, and Power Platform’s virtual network support lets custom connectors reach private services.
Authentication differs too. Claude accepts OAuth 2.0, where each user signs in with their own account, a static credential that an Owner enters once (in beta), or no authentication. OpenAI expects OAuth 2.1 as the MCP authorization spec describes, with dynamic client registration, client ID metadata documents or a predefined client. Copilot Studio offers no authentication, an API key or OAuth 2.0. Whatever the client, enforce authorization inside the MCP server on every request rather than relying on the model, as OpenAI’s guidance puts it.
Before building anything, check whether the software vendor already offers an MCP server for your edition. Build a custom server when you need your own fields, business rules, approval steps or reach into on-premises systems.
| Client | Where calls come from | Private systems | Admin control |
|---|---|---|---|
| Claude connectors | Anthropic’s cloud, from published IP ranges | Allowlist Anthropic, or use local servers in Claude Desktop or Claude Code | Owners add connectors; each member signs in |
| ChatGPT plugins | OpenAI, to a public HTTPS endpoint | Secure MCP Tunnel with an outbound-only client | Plugins and actions enabled by role |
| Copilot Studio | Power Platform connectors in Microsoft’s cloud | Power Platform virtual network support for custom connectors | Data policies; blocking a connector blocks its MCP tools |
Reference: Microsoft: connect Copilot Studio to an existing MCP server
Developer platforms.
For applications you build yourself, compare model platforms, not assistants. Anthropic offers the Claude API directly and through Amazon Bedrock, Claude Platform on AWS, Google Cloud’s Agent Platform and Microsoft Foundry, and feature availability varies by platform. It includes the Messages API, Claude Managed Agents and an MCP connector, in beta, that calls remote MCP servers from the API.
OpenAI’s API offers the Responses API, which can call remote MCP servers, or private ones through Secure MCP Tunnel, plus the Agents SDK, the Agents API and Agent Builder. The API Platform is a separate account from any ChatGPT workspace, with its own keys and billing.
Residency and retention work differently on the APIs than in the chat products. The Claude API can pin inference to the US per request, and its workspace storage is currently US-only. OpenAI offers per-project data residency to eligible customers and keeps abuse-monitoring logs for up to 30 days unless you are approved for zero data retention or modified abuse monitoring.
Microsoft splits the work between Copilot Studio, a low-code studio for agents and workflows, and Microsoft Foundry, where developers build agents with models from Microsoft, OpenAI, Anthropic, Meta and others. For engineering teams, the coding tools to compare are Claude Code, OpenAI’s Codex and GitHub Copilot.
- Where must inference run, and does your preferred platform offer that region?
- Which features do you need on day one, and are they available on your cloud channel?
- Who owns API keys, spend limits and model version changes?
- Can the platform reach your MCP servers, or do you need a tunnel or an allowlist?
Licensing models at a high level.
All three mix per-user licenses with usage-based charges, and the mix differs. The table describes how each product is sold, not what it costs. Prices change, so confirm them on the vendor’s pricing page or with your account team before you budget.
Two points catch buyers out. A Claude or ChatGPT subscription does not include API usage, which is billed through a separate account. And on Claude Enterprise, the seat fee covers access only and all usage is billed at API rates, so spend limits matter from the first day.
| Product | How it is sold | Usage-based elements |
|---|---|---|
| Claude Team | Per seat, Standard or Premium, billed monthly or annually | Optional usage credits |
| Claude Enterprise | Per seat for access, billed annually | All usage billed at API rates, with spend limits |
| ChatGPT Business | Per user, two or more users, billed monthly or annually | ChatGPT credits to extend usage |
| ChatGPT Enterprise | Through OpenAI sales | Credit-based billing in some workspaces; ChatGPT Work and Codex share usage |
| Microsoft Copilot | Per-user add-on to qualifying Microsoft 365 plans; included in Microsoft 365 E7 | Copilot Cowork and some agents use Copilot Credits |
| Copilot Studio and Agent 365 | Copilot Studio through Copilot Credits; Agent 365 per user | Pay-as-you-go, prepurchase plans or prepaid packs |
| Claude API | Pay per use, direct or through AWS, Google Cloud or Microsoft Azure | Token-based usage; features vary by platform |
| OpenAI API | Pay per use through an API Platform organization | Token-based usage, separate from ChatGPT |
How to decide.
Score each option against your own workflows, not a generic feature list. Take two or three real tasks, run them in a pilot with real permissions, and compare the results, the admin effort and the cost model. These questions usually settle it.
- Where does the work happen today: Microsoft 365 apps, a browser, a terminal or your own application?
- Which systems must the assistant read, and which must it change? List them by name and edition.
- Can each vendor’s cloud reach those systems, or do you need a tunnel, an allowlist or a local server?
- Which controls does your security review require: SCIM, audit export, retention periods, residency or customer-managed keys?
- Do you also need a developer platform, and which cloud do you already buy from?
- Who will own the product, the connectors and the budget after launch?
Rollout considerations for all three.
The rollout pattern is similar whichever product you choose. Fix identity and permissions first, pilot one workflow with a named owner, start connectors with read-only tools, and test with an account that has only the intended access. Making a connector or plugin available does not grant access in the source system; users still need their own permissions there.
Plan for change. Recent examples: Microsoft renamed Microsoft 365 Copilot to Microsoft Copilot, Anthropic is merging Cowork into the main Claude app, and OpenAI is retiring custom GPTs in ChatGPT Enterprise in favor of plugins. Keep an owner who reads the release notes and a short list of settings to recheck after each change.
AIONDATA is an independent consultancy with leadership in San Ramon, California and engineering in Noida, India. We are not a partner of Anthropic, Microsoft or OpenAI. We help teams scope the choice, build custom MCP servers for systems such as SAP, NetSuite, Salesforce and HubSpot, and run technical training.
- Clean up SharePoint and shared-drive permissions before any assistant can search them.
- Turn on SSO, provisioning and audit export before inviting the pilot group.
- Start each connector with read-only tools and add writes with an approval step.
- Test with a restricted account as well as an administrator.
- Name owners for the workspace, each connector and the budget.
Put the plan into practice.
Bring one workflow and the systems involved. We can help define the implementation, integration or training scope.