The short answer
For most organizations, the deciding factor is where work already happens. If you run on Microsoft 365, Microsoft 365 Copilot works inside Outlook, Teams, Word and Excel with your existing permissions. If you run on Google Workspace, Gemini does the same in Gmail, Docs and Drive. ChatGPT's business plans are a strong standalone assistant, useful when people work across many tools or want one general-purpose workspace.
All three vendors state that their business offerings do not use your data to train models by default, so compare them on reach, admin controls and integration instead. When you need answers from specific systems under strict control, a custom assistant is often the better fit. Plans and features change often: check each vendor's current terms and pricing before you decide.
Promatics is not a partner or reseller of any of these vendors. We recommend on fit.
Where each one fits
- Microsoft 365 Copilot, which Microsoft has renamed Microsoft Copilot, is built into the Microsoft 365 apps and grounded in the emails, chats, meetings and documents each user can already access (Microsoft Learn). Microsoft also offers Copilot Chat, a web-grounded chat with enterprise data protection that uses organizational content only in specific ways, such as files a user adds to a prompt (Microsoft Learn).
- Gemini in Google Workspace works in Gmail, Docs, Drive and Meet, alongside the Gemini app and Gemini Notebook (formerly NotebookLM), when used with a qualifying Workspace edition (Google).
- ChatGPT Business and ChatGPT Enterprise give staff a dedicated workspace, with apps that connect to internal sources and third-party applications your admins enable (OpenAI). OpenAI's API platform is a separate route for building your own solutions.
If you use both Microsoft 365 and Google Workspace, or neither is central, the "where does work live" test matters less, and a standalone or custom assistant deserves a closer look.
How each handles your organization's data
This table summarizes each vendor's own business privacy page as of October 2026. Terms change, so treat it as a starting point and confirm against the current versions.
| Microsoft 365 Copilot | ChatGPT business plans | Gemini in Google Workspace | |
|---|---|---|---|
| Training on your data | Prompts, responses and Microsoft Graph data are not used to train foundation models | Not used for training by default, unless you opt in to share data | Not used to train models without your prior permission or instruction |
| What it can reach | Organizational content the user can at least view | Internal sources connected through apps your admins enable | Workspace content the user has permission to access |
| Existing permissions | Respected, per Microsoft | Respected for connected apps; each user authenticates | Respected, per Google |
| Human review of content | Opted out of Azure OpenAI abuse monitoring, which includes human review | Limited, and varies by plan | Not human reviewed outside your domain without permission |
| Examples of admin controls | Choose which agents are allowed; retention and search through Microsoft Purview | SAML single sign-on; control over access, features and apps; retention settings | Turn the Gemini app on or off; set conversation retention; data loss prevention on generated content in supported editions |
Two cautions apply whichever you choose. First, these commitments cover business offerings, not personal accounts: OpenAI, for example, says it uses data from its services for individuals to train its models. Make sure staff use work accounts. Second, ask where prompts are processed for your plan. Microsoft says customers outside the EU may have Copilot queries processed in the US, the EU or other regions, while core Microsoft 365 content for US tenants is usually stored in Microsoft's United States datacenter geography; Google notes that Workspace data region settings do not apply to Gemini Notebook. The FTC Act, state privacy laws and sector rules such as HIPAA apply to personal information staff put into any of these tools (FTC). This is general information, not legal advice.
Questions to ask every vendor
- Can we enforce single sign-on and multifactor authentication, and add and remove users automatically?
- Can administrators set retention and search or export prompts and responses for an investigation?
- Do our data loss prevention rules apply to prompts and outputs?
- Which connectors, apps and agents can users add, and can we approve each one?
- Which models and subprocessors are used, and can we choose? (Microsoft, for instance, lets administrators decide whether to use the Anthropic and OpenAI models it offers in Copilot.)
- Is web search used to ground answers, and can we turn it off?
- Where are prompts processed and stored for our plan and region?
Integration with your other systems
None of these assistants knows your ERP, CRM or line-of-business applications out of the box. Connecting them is where most of the real work sits, whether that is a connector, an app or an agent. Options differ by vendor and plan and change often, so test the exact connection you need, with real permissions, during a pilot. If your operations run on Prometheus or ERPNext or another business system, plan the integration as its own piece of system integration work, not an afterthought.
When a custom assistant is better
A general assistant is the right default for everyday drafting, summarizing and searching. A custom AI assistant is often better when:
- answers must come only from approved sources, with citations people can check;
- the information lives outside the productivity suite, in an ERP, CRM, document system or file shares;
- permissions are complex, such as client matters, health records or project teams;
- you need control over the model, where processing happens and what is logged;
- the assistant belongs inside your own portal or application;
- use is concentrated in a few processes, so a per-user license for everyone does not fit.
Our guide to how AI assistants answer from your documents explains the approach. Many organizations end up with both: a suite assistant for everyday work and a custom one for a specific process.
If your policies do not allow confidential information to reach any outside AI provider, there is a further option: a private assistant running an open-weight model on servers you control. Our guide to private AI and self-hosted models explains what that involves.
Rather talk it through? If you are weighing Copilot, ChatGPT and Gemini, or wondering whether you need something custom, we can compare them against your systems, data and controls. Talk to a Promatics specialist
How to decide
- Where does work live? Microsoft 365, Google Workspace or a mix.
- What must the assistant reach? Email and documents only, or also ERP, CRM and other systems.
- What controls are non-negotiable? Retention, data loss prevention, data location, approval of connectors.
- Pilot on real tasks. A small group, real work, agreed measures and, where you can, two options side by side.
- Confirm current terms and pricing with the vendor before you sign, rather than relying on comparison articles, including this one.
When to bring in help
If your organization runs on one platform, has tidy permissions and needs everyday productivity help, you can usually choose the matching assistant and run a short pilot under a clear policy.
Bring in help when you run mixed platforms, handle health, financial or client confidential data, need the assistant to reach your business systems, or must show leadership evidence before buying. For Microsoft 365 organizations, our Microsoft 365 Copilot service covers readiness, oversharing clean-up, pilot and adoption. For Google Workspace organizations, or when no single platform fits, our AI strategy and readiness work compares the options on your own tasks. Because we are not tied to any vendor, our recommendation follows your systems, data and budget.
Sources and further reading
Product capabilities and guidance change. These are the primary sources this article relies on, checked on the review date above.
- Data, privacy and security for Microsoft Copilot, Microsoft Learn
- Microsoft Copilot Chat privacy and protections, Microsoft Learn
- Enterprise privacy at OpenAI, OpenAI
- Generative AI in Google Workspace Privacy Hub, Google Workspace
- Privacy and security business guidance, Federal Trade Commission
This article is general information, not legal, accounting or security advice for your specific situation. Examples are hypothetical unless stated otherwise.