Slack vs. Microsoft Teams (2025): Feature Face-Off for Remote Teams
By Sima Team | June 8, 2025
TL;DR – Slack keeps the UX crown with Agents in Channels, Canvas docs, and 2× faster desktop app, while Microsoft Teams bundles deep Copilot 365 AI, tighter M365 integration, and cheaper seats for enterprises already on E3/E5. Agencies who live in design/dev tool chains lean Slack; corporates embedded in Office 365 save 40 % sticking with Teams. See the 2025 feature matrix and ROI math below.
Why Re-evaluate in 2025?
- Slack Agents API (May 2025) lets AI bots participate in threads natively—think Jira bot, Sima feedback bot, etc. (slack.com)
- Slack Canvas GA (April 2025) replaces Google Docs-in-Slack add-ons with native rich docs pinned to channels. (slack.com)
- Teams 2.0 rolled out a new WebAssembly engine, halving RAM and boosting FPS on video. (techcommunity.microsoft.com)
- Microsoft Copilot for Teams now summarises meetings, drafts replies, and preps agendas using Graph data. (microsoft.com)
Quick Verdict Table
| Scenario | Best Pick | Why |
|---|---|---|
| Design / dev agencies | Slack Pro/Business+ | Best app integrations (Figma, GitHub, Jira), Agents API, Canvas meeting docs |
| O365 enterprises (>300 seats) | Teams E3/E5 | Included in license, Copilot 365 AI summaries, SharePoint & OneDrive native |
| Freelance or small startup | Slack Free | 90-day history, unlimited integrations, new Huddles HD |
| Government / high-compliance | Teams GCC-High | FedRAMP, HIPAA, eDiscovery baked-in |
| Hybrid org needing shared chats with vendors | Slack Connect | Cross-org channels w/out tenant switching |
Feature Matrix (June 2025)
| Feature | Slack (Pro) | Microsoft Teams |
|---|---|---|
| AI assistant | Slack AI summarise; Agents in Channels (open platform) | Copilot 365 meeting recaps, inline replies |
| Shared channels | Slack Connect (up to 250 orgs) | Microsoft Teams Shared Channels (max 25 orgs) |
| In-line docs | Canvas rich docs + whiteboards | Loop components + OneNote |
| Video calls | Huddles 2.0 (under 50 participants), Zoom levels of latency | Up to 1,000 live event attendees |
| Storage per user | 10 GB (Pro) | 1 TB OneDrive + 10 GB SharePoint |
| Integrations / apps | 2,600+ | ~1,100 |
| Pricing (entry paid) | $8.25 per user/mo (Pro) | $4 (Teams Essentials) or included in M365 |
| Admin / compliance | Enterprise Key Management, Audit API | eDiscovery, DLP, Litigation Hold built-in |
What's New in 2025
Slack Highlights
- Agents API – bots join private threads automatically; perfect for Sima feedback bot posting task summaries.
- Canvas Docs – persistent, versioned docs inside channels—replaces pinned Google Docs.
- Huddles 2.0 – 1080p screen share, collaborative cursors, and spatial audio.
Teams Highlights
- Copilot 365 – Auto-create meeting recaps, action items, sentiment analysis.
- Teams 2.0 Engine – 50 % less RAM, twice the FPS on 4K calls.
- Mesh for Teams – lightweight 3D breakout rooms for workshops (no VR hardware needed).
ROI Calculation Example (120-Person Remote Agency)
| Metric | Slack Business+ | Teams (M365 E3) |
|---|---|---|
| License cost/user/mo | $15 | Included (E3 $36, but org already pays) |
| Monthly platform cost | $1,800 | $0 incremental |
| Integrations saved (Jira, PagerDuty alerts) | 6 h eng/wk | 4 h (needs Power Automate scripts) |
| Billable rate | $120 | $120 |
| Value of time saved | $3,120 | $2,080 |
| ROI | 1.7× | ∞ (no extra cost) |
Methodology: Time-saved based on Sima plug-in telemetry April–May 2025 across 3 global agencies.
Pros & Cons Recap
| Slack ✅ | Slack ❌ | Teams ✅ | Teams ❌ | |
|---|---|---|---|---|
| UX speed | Fast, intuitive | Thread vs DM split can confuse | Single-pane chat/meetings | UI slower on old Macs |
| Integrations | Massive catalog, open API | Some enterprise security gaps | Deep M365 integration | Fewer 3rd-party app actions |
| AI features | Agent platform, Slack AI summaries | Full Copilot requires add-on | Copilot deep Graph context | Copilot only on E3/E5 |
| External channels | Slack Connect easy cross-org | 2-org limit on free | Shared Channels | Tenant switching cumbersome |
Who Should Choose Which?
- Dev-heavy, tool-sprawl agencies – Slack Pro/Business+ for integrations + Agents.
- Enterprises already on O365 – Stick with Teams, leverage Copilot.
- Client-service firms working cross-org – Slack Connect reduces guest account chaos.
- Highly regulated sectors – Teams GCC-High or Slack Enterprise Grid + EKM—evaluate audit needs.
FAQs
Is Slack Free still limited to 90-day history?
Yes, but Canvas docs and channel files remain accessible beyond that window.
Does Copilot cost extra?
Copilot 365 add-on is $30 user/mo; Teams Essentials tier has Copilot light (meeting summaries only).
Can you run both?
Many agencies do—Slack for engineers, Teams for client calls. Sima's Time-Tracker shows context-switch overhead at ~15 min/day.
Final Recommendation
If your workflows revolve around dev/design integrations and cross-org channels, Slack delivers a more flexible, AI-ready platform in 2025. If you're already invested in Microsoft 365 and need enterprise-grade compliance with no extra spend, Teams wins on TCO—especially with Copilot baked in.
Next Step: Trial each for a sprint. Track context-switch time with Sima's Time-Tracker and let data decide.
Happy collaborating!