Compare structures, not benchmarks
Model leaderboards reshuffle quarterly; the platforms' SHAPES don't. The four axes that actually decide enterprise fit:
| Axis | M365 Copilot | ChatGPT Enterprise-class | Gemini (Workspace) |
|---|---|---|---|
| Native grounding | Your M365 corpus, permission-trimmed, zero setup | Connectors/uploads you configure and maintain | Native to Google Workspace corpus |
| Identity & access | Entra end-to-end: CA, existing DLP/labels apply | Own identity + SSO; enterprise controls maturing on their own track | Google identity stack |
| Compliance surface | Interactions are M365 records: Purview audit/eDiscovery/retention out of the box | Admin controls + APIs; records live in a NEW system your legal team must onboard | Vault-integrated |
| Where work happens | Inside Word/Excel/Teams — the artifact stays in flow | A destination app; output pasted back | Inside Workspace apps |
The honest structural read: if your corpus and identity live in Microsoft 365, Copilot's integration advantages are architectural, not marketing — grounding without connector projects, compliance without new systems. A frontier-model preference is a real reason to ALSO run another tool; it is a weak reason to replace the grounded one.
The coexistence reality (what actually happens)
Most estates end up hybrid: Copilot for grounded work, another assistant for some teams' preferences, plus unsanctioned consumer AI regardless of policy. Which turns the comparison into a GOVERNANCE portfolio question:
- Sanction explicitly (which tools, for what data classes) — silence creates shadow usage with zero controls.
- Point DSPM for AI / endpoint DLP at the whole portfolio (security module) — visibility over BYO-AI is a Purview feature now, use it.
- Route by data class: tenant-data prompts belong in the tool whose records and trimming you control.
What to watch (proofs)
- The shadow inventory: DSPM for AI's third-party AI usage reporting + network/CASB telemetry — the actual portfolio, not the sanctioned one.
- Records parity test: run the same sensitive prompt in each sanctioned tool, then find it in each tool's audit surface — the compliance-surface row of the table, verified by your own legal team.
- Renewal math: per-seat costs against measured usage per tool (operations module) — portfolio pruning is an annual discipline.