Short answer
Microsoft Teams fits businesses already on Microsoft 365 that want chat, meetings, calling and file collaboration in one place tied to SharePoint and Entra ID. Slack fits teams that live in chat, work heavily with outside organizations in shared channels and rely on a wide range of non-Microsoft apps. Both are mature. Standardizing on one reduces confusion and security gaps.
Key facts
- Teams stores channel files in SharePoint and chat files in OneDrive.
- Slack Connect lets separate organizations share channels.
- Teams shared channels let you collaborate with other Microsoft 365 organizations.
- Some Microsoft 365 suites are sold with or without Teams, so check your plan.
- Running both tools usually means duplicated conversations and files in two places.
The short comparison
Teams and Slack both offer persistent chat, channels, direct messages, integrations and calling features. Slack began as a chat-first product and is known for its fast messaging experience and large app ecosystem. Teams grew into a hub for Microsoft 365, combining chat with meetings, phone, files and apps.
The table reflects stable differences. Both products add features often, so confirm current details before deciding.
| Area | Microsoft Teams | Slack |
|---|---|---|
| Chat and channels | Teams, channels, group and one-to-one chat | Channels, direct messages and threads |
| Meetings | Full meetings, webinars and town halls | Huddles for quick audio and video, with integrations for larger meetings |
| Phone system | Teams Phone add-on with PSTN options | Not a core business phone system |
| Files | SharePoint and OneDrive with Office co-editing | File sharing plus integrations with storage services |
| External collaboration | Guest access and shared channels | Slack Connect shared channels |
| Integrations | Microsoft apps, Power Automate and a third-party app store | Large app directory and Workflow Builder |
| Identity | Entra ID with Conditional Access | SSO with your identity provider |
| Governance | Microsoft Purview retention, eDiscovery and DLP by plan | Admin, retention and compliance features by plan |
When Teams is the better fit
- You already pay for Microsoft 365 and want to avoid a second collaboration license.
- You need meetings, webinars and a business phone system in the same app as chat.
- Teams work centers on Word, Excel and PowerPoint files stored in SharePoint.
- You want one set of retention, eDiscovery and DLP policies across email, chat and files.
- You use Teams Rooms or plan to equip meeting rooms.
When Slack is the better fit
Slack is a well-designed product with loyal users. If your business does not depend on Microsoft 365 for meetings and files, or chat is your main workspace, Slack may be the more natural standard.
- Your work happens mostly in chat and people value its speed and threading.
- You collaborate daily with many outside companies in shared channels.
- Your developer, product or support teams rely on Slack integrations and bots.
- Your productivity suite is Google Workspace or a mix of vendors.
- Slack culture is well established and moving would cost real goodwill.
Why standardizing matters
Many companies run both tools by accident. One department uses Slack, another uses Teams, and decisions get split across two places. That creates search gaps, duplicate files, more admin work and two sets of external access to secure.
Pick one primary tool for internal chat, set a clear rule for external collaboration, and define where files of record live. If one group must keep the other tool for a client requirement, document it as an exception with an owner and review date.
Moving from Slack to Teams
A move to Teams starts with mapping Slack channels to Teams teams and channels, not copying them one-for-one. Many old channels can be archived. Decide which message history must move, which can be exported for records, and which can stay read-only for a period.
Third-party tools can migrate Slack messages and files into Teams, with limits on formatting, reactions and integrations. Rebuild key Slack workflows in Power Automate or Teams apps, train channel owners first, and set a firm date when Slack becomes read-only.
- Inventory channels, owners, integrations and Slack Connect partners.
- Design a simple Teams structure with naming and ownership rules.
- Decide on history: migrate, export or archive.
- Pilot with one department, then move the rest in waves.
How Accred Consulting approaches it
Accred Consulting looks at how your teams actually collaborate, what you already license and what external partners expect, then recommends a standard. When Teams is the right choice, Accred plans and runs the move from Slack: discovery covers channels, integrations, history and external partners, and the proposal sets scope, a fixed price and timeline. US-based specialists design the Teams structure and governance, migrate selected history, rebuild key workflows and train owners. Handover includes documentation and knowledge transfer.
Track record: 475+ client projects, 2,000+ migration workstreams and 210,000+ users migrated by a US-based team. Company facts · Case studies
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