Microsoft Teams vs Slack for Business: The Real Differences

Slack changed how teams talk to each other, and plenty of people still prefer it — for good reasons. But if your business also pays for Microsoft 365, you're carrying two bills for tools that overlap almost completely, and one of them is already covered. Here's an honest look at where each one actually wins.

This isn't a hit piece. Slack is a genuinely well-made product, and "Teams is included" is not automatically a winning argument — a tool your team hates using is expensive at any price. The real question isn't which app is better in a vacuum. It's which one is better for your business, given the licenses you already hold, the files you already store, and the compliance questions you already have to answer.

So let's give both sides a fair hearing, look at the money, then at what a switch actually involves.

Where Slack genuinely wins

The messaging experience

Slack's core chat is still the most polished in the business. The quick switcher, threads that stay readable, drafts, reminders, saved items, keyboard-first navigation — it all feels fast and considered. People who live in chat all day notice the difference, and pretending otherwise convinces nobody. Teams has closed much of the gap, but Slack set the standard and largely still holds it.

The integrations culture

Slack's app directory is enormous, and more importantly, posting into Slack is the default way developer tools announce things. Build alerts, deploy notifications, monitoring pings, support tickets — if a tool can send a webhook, someone has already wired it into Slack. Engineering-heavy companies often have years of this plumbing in place, and it works. Teams supports the same patterns, but Slack's ecosystem got there first and the habits run deep.

Huddles

Huddles nail a specific thing: low-ceremony audio. One click, no invite, no "can you see my screen?" ritual — the digital equivalent of leaning over a desk. Teams can do ad-hoc calls too, but its centre of gravity is the scheduled meeting. If your culture runs on spontaneous two-minute conversations, Huddles genuinely fit the way you work.

Where Teams wins for business

It's already in your subscription

Teams is included in most Microsoft 365 Business and Enterprise plans. Not a trial, not a stripped-down tier — the full product: chat, channels, meetings, file sharing, apps. If your company pays for Microsoft 365 so people can use Outlook, Word and Excel, you very likely already own Teams. That single fact reshapes the whole comparison, and we'll come back to it below.

Files are real files, backed by SharePoint

In Slack, a file is an attachment stuck to a message. In Teams, every file shared in a channel lands in a SharePoint document library — which means version history, co-authoring in Word and Excel, proper permissions, retention policies and search that actually finds things. Six months later, the contract isn't buried in a scroll of chat; it's in a library, current version on top. If you've read our piece on the Microsoft 365 tools most teams ignore, you'll recognise the pattern: Teams is the friendly front door to infrastructure you already own.

Meetings and calendar live in Outlook

Teams meetings are native to the Outlook calendar. Scheduling, availability, room booking, the join button in the invite, recordings and transcripts filed automatically — none of it needs a plugin or a copy-pasted link. Slack does calls and integrates with calendars, but it isn't trying to be your meetings platform. For most businesses, that means running Slack plus a separate meetings tool. Teams is both.

Approvals and the Power Platform, inside the chat

This is the difference that surprises people most. Teams isn't just a chat app; it's a surface for actual business processes. The built-in Approvals app handles sign-offs without leaving the conversation. Power Automate flows can post requests into a channel and collect the response. A Power App — a leave request form, an inspection checklist — can be pinned as a tab right where the team already works. Chat stops being where work is discussed and becomes where work is done.

Guest access and compliance through Purview

If you operate under any kind of regulatory or legal scrutiny, this section pays for the whole article. Teams inherits Microsoft 365's governance stack: Microsoft Purview gives you retention policies, eDiscovery, data loss prevention and sensitivity labels across chats and the files behind them, managed in one place. Guest access is controlled per team, with external users clearly badged. Slack offers serious compliance tooling on its enterprise tier — but on Teams these controls come with the platform and cover your email and documents too, under one policy.

The cost reality: the bill you’re paying twice

Here's the conversation we have most often. A business pays for Microsoft 365 — because everyone needs Outlook and Excel — and also pays for Slack, per user, per month. Two subscriptions; one need. The Slack line isn't buying a capability the business lacks. It's buying a preference.

When Slack still makes sense

A fair comparison has to say this part out loud. Keep Slack — happily, without guilt — if any of these describe you:

• You're not on Microsoft 365. If you run Google Workspace or no suite at all, the "already included" argument evaporates and Slack competes on pure merit — where it does very well.
• Your engineering workflow is welded to it. Years of integrations, bots and incident-response channels are real infrastructure. Rebuilding them has a cost, and it isn't small.
• Your network runs on Slack Connect. If your clients, agencies and partners all reach you through shared Slack channels, leaving has a relationship cost as well as a technical one.
• Chat is genuinely your whole workflow and your team's fluency in Slack is a productivity asset you'd rather not disturb this year.

What we'd gently challenge is the middle position: paying for both indefinitely, with Teams used for meetings and Slack for chat, files scattered across each, and nobody quite sure where anything lives. That's the worst of both worlds — double the cost, double the places to search.

If you do switch: migration notes from the field

Map your channels before you move anything

Don't recreate your Slack workspace one-for-one. Slack encourages hundreds of flat channels; Teams organises into teams, each with channels inside. Audit what you have, archive the dead ones — every workspace has them — and group what's left into a sensible team structure. A messy Slack rebuilt as a messy Teams just moves the clutter. This is also the moment to decide where files will live, because in Teams that decision is really a SharePoint structure decision.

Know what history actually moves

Set expectations early, because this surprises people. Third-party migration tools can copy public and private channel messages into their new Teams channels, generally preserving who said what and when. Direct messages, emoji reactions, threads and app-posted content move imperfectly or not at all. The pragmatic play: migrate the channel history that matters, export a complete Slack archive for record-keeping and compliance, and let DMs start fresh.

Cut over hard, one group at a time

Rebuild the critical integrations first, move one department at a time, and make Slack read-only for each group as it lands. Give people a short "where did everything go?" guide — most of the friction in a switch is that first week. A little training up front beats a month of grumbling.

This is exactly the work our Microsoft Teams solutions practice does: channel mapping, migration, governance, and wiring in the approvals and apps that make Teams more than a chat window. And if you want to see what else your subscription is quietly capable of, the rest of the blog is full of it.

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The bottom line

Slack is the better pure chat app. Teams is the better business platform — files, meetings, approvals and compliance in one place, on a license you're probably already paying for. If you're not on Microsoft 365, or Slack is load-bearing infrastructure for your team, staying put is a rational choice. But if you're paying for both and using half of each, you owe yourself the comparison — done honestly, with your own numbers on the table.