In short: For UK businesses already using Microsoft 365, Teams is the stronger default choice - it is already included in most M365 subscriptions, integrates natively with Outlook and SharePoint, and connects directly to Microsoft Copilot AI. Slack is a credible alternative for teams that prefer a more focused messaging experience, work across platforms outside Microsoft, or are embedded in Salesforce. Many businesses run both for different purposes, which is a perfectly valid approach.
ⓘ Note on Teams unbundling (November 2025): From November 2025, Microsoft was required to offer Microsoft 365 globally both with and without Teams bundled. For most UK businesses already on Microsoft 365 who use Teams, this has no practical impact - Teams remains included in existing subscriptions. It does, however, mean Teams is now available as a standalone purchase for businesses that want it without the full Microsoft 365 suite.
Feature comparison at a glance
Pricing is indicative as of early 2026 in GBP. Teams pricing shown as part of a Microsoft 365 Business Basic subscription, which includes Teams plus Outlook, Exchange, SharePoint, and OneDrive.
| Microsoft Teams | Slack | What this means for your business | |
|---|---|---|---|
| Included with M365 | Yes — all paid M365 plans | Separate subscription | For M365 customers, Teams adds no incremental cost |
| Starting price | Included in M365 Business Basic ~£4.90/user/month Or standalone Teams Essentials |
Pro from ~£7.25/user/month (messaging only, no bundled apps) |
Teams significantly cheaper if you need M365 apps anyway |
| Video meetings | Up to 300 participants Breakout rooms, live events |
Huddles (audio/video) up to 50 Full video via integrations |
Teams is the stronger platform for meeting-heavy organisations |
| Microsoft 365 integration | Native & deep Outlook, SharePoint, Word, Excel, PowerPoint |
Third-party integrations available | Co-editing documents in Teams is a key differentiator |
| Copilot AI | Microsoft Copilot Meeting summaries, chat recap, action items |
Slack AI (separate cost) Thread summaries, recaps, search |
Copilot deeper across the Microsoft stack; Slack AI strong for messaging |
| Salesforce integration | Via Teams app store | Native — deep integration Agentforce in Slack (GA Jan 2025) |
Slack is the better choice for Salesforce-first organisations |
| Third-party integrations | 700+ apps in Teams store | 2,600+ apps | Slack broader ecosystem; Teams deeper within Microsoft |
| Messaging experience | Structured channels and threads Improved threading in 2025 |
Chat-first design Widely rated more intuitive |
Slack edges ahead for day-to-day messaging UX |
| File storage | SharePoint and OneDrive (included) | Via integrations (Google Drive, Dropbox etc.) | Teams provides file storage natively; Slack depends on connected tools |
| Free tier | Yes — limited features | Yes — 90 days message history | Both have usable free tiers for small teams getting started |
| Market share | ~320M monthly active users / ~37% market share | ~79M daily active users / ~13% market share | Teams dominant; Slack strongest in tech and creative sectors |
Understanding each platform
Microsoft Teams
Teams is Microsoft’s all-in-one collaboration platform, included with Microsoft 365. It combines persistent chat, video and audio meetings, file storage via SharePoint, and deep integration with Office apps. In 2025, Microsoft addressed longstanding user feedback about conversation organisation with improved threading and personalisation options. Microsoft Copilot in Teams provides AI meeting summaries, real-time transcription, and chat recaps.
- Already included in Microsoft 365 subscriptions at no extra cost
- Native co-editing of Word, Excel, and PowerPoint documents in channels
- Copilot meeting summaries and action items built in
- Up to 300 participants in meetings; breakout rooms; live events
- Phone system integration available via Teams Phone
Slack
Slack is a messaging-first collaboration platform owned by Salesforce since 2021. It is known for its clean, fast interface, extensive third-party app ecosystem (2,600+ integrations), and flexibility across different technology stacks. Slack AI across all paid plans in 2025 provides thread summaries, channel recaps, and daily highlights. Its native Salesforce integration, including Agentforce in Slack (available from January 2025), makes it the preferred tool for Salesforce-centric organisations.
- Widely rated more intuitive for daily messaging workflows
- 2,600+ third-party integrations across most business tools
- Native Salesforce and Agentforce integration
- Slack AI included on all paid plans from 2025
- Flexible across non-Microsoft technology stacks
Which platform fits your business?
Choose Microsoft Teams if…
- You already pay for Microsoft 365 — Teams is already included
- Meetings, video calls, and live events are a major part of how your team communicates
- You want document co-editing inside your communication tool
- Microsoft Copilot AI in meetings and chat is a priority
- Your CRM is Dynamics 365 rather than Salesforce
- You want phone system capabilities via Teams Phone
- Simplicity of a single Microsoft vendor for productivity tools matters
Consider Slack if…
- Your primary CRM is Salesforce and Agentforce integration matters
- Your team works across a diverse non-Microsoft technology stack
- Messaging-first collaboration is more important than meetings
- You collaborate extensively with external parties already on Slack
- Your team is in a tech or creative sector where Slack is the cultural norm
- You want the broadest possible third-party app integration options
Frequently Asked Questions — Microsoft Teams vs Slack
Common questions from UK businesses evaluating Microsoft Teams and Slack — answered by Advantage, Microsoft Solutions Partner.
Is Microsoft Teams better than Slack?
For businesses already using Microsoft 365, Teams is typically the better primary choice — it is already included in most M365 subscriptions, integrates natively with Outlook and SharePoint, and connects directly to Microsoft Copilot AI. The value proposition is compelling: for businesses that need Microsoft 365 apps anyway, Teams comes at no additional cost.
Slack is a strong alternative for teams that prefer a more focused messaging experience, work across platforms outside Microsoft, or are embedded in the Salesforce ecosystem. Many businesses run both — Teams for meetings and document collaboration, Slack for messaging or external project channels.
Is Microsoft Teams free?
Teams has a free tier with limited functionality. For most UK businesses, Teams is included as part of a Microsoft 365 subscription at no additional cost — so if you already pay for Microsoft 365 Business Basic, Standard, or Premium, Teams is included. As of November 2025, Teams is also available as a standalone purchase following Microsoft’s global unbundling requirement.
How much does Slack cost compared to Teams?
Slack’s Pro plan starts at approximately £7.25 per user per month (billed annually) — messaging only, with no bundled productivity apps or file storage. Microsoft 365 Business Basic, which includes Teams plus Outlook, Exchange, SharePoint, and OneDrive, starts at approximately £4.90 per user per month.
For businesses that need Microsoft 365 apps alongside a collaboration tool, Teams is significantly more cost-effective. For businesses that only need a messaging tool and do not use the broader Microsoft 365 suite, the comparison is closer — though Slack still tends to come out more expensive on a per-user basis.
What happened with Microsoft Teams unbundling in 2025?
From November 2025, Microsoft is required to offer Microsoft 365 and Office 365 plans globally both with and without Teams bundled. This was the result of regulatory pressure, notably from the EU, following a competition investigation into whether Microsoft was unfairly leveraging its market position to favour Teams over competitors like Slack.
In practice, for most UK businesses already using Microsoft 365 and Teams, nothing changes — Teams remains included in their existing subscriptions. The change means Teams is now also available as a standalone product, and M365 subscriptions without Teams are available for organisations that genuinely prefer a different collaboration tool.
Can you use both Teams and Slack?
Yes — around 66% of companies using Teams also use Slack in some capacity. Common hybrid approaches include using Teams for internal meetings, calls, and document collaboration while using Slack for specific project channels, external collaboration with clients or agencies on Slack, or developer teams that prefer Slack’s interface. The two tools are not mutually exclusive and running both is a legitimate operational choice for many businesses.
Does Teams work with Dynamics 365 and Business Central?
Yes — Teams integrates natively with both Dynamics 365 Sales and Business Central. Business Central data can be shared directly in Teams channels and chats, allowing users to view customer, supplier, or financial records within Teams without switching applications. Dynamics 365 Copilot for Sales provides AI-assisted deal insights and meeting summaries within Teams for sales teams.
This Microsoft-stack connectivity is one of the strongest arguments for Teams over Slack for businesses running Dynamics 365 or Business Central.
Does Advantage help businesses deploy Microsoft Teams?
Yes — Teams configuration, SharePoint integration, and Microsoft Copilot deployment in Teams are part of Advantage’s Microsoft 365 managed services. We help UK SMEs get Teams working properly as part of a wider Microsoft 365 deployment, not just switched on.
Visit our Microsoft 365 & Copilot page or call 020 3004 4600 for more information.
