Roles and channel permissions. I can't assign a role to someone and grant them granular permissions in slack like I can discord. I'm either a guest, user, admin or owner.
Slack does app integrations and bots pretty well.
Slack does app integrations and bots pretty well.
To give an example, let's say you have both a Discord channel and a Slack channel with the same 10 people working on a project, 7 of which are software developers. To mention the developers, your Slack option is either @everyone (including 3 non-developers) or individually. On Discord you can create @developers and add only those seven, not bothering the other 3.
You can really go buckwild with that basic concept: only admin can tag @everyone, only @talkers can join a voice channel, only @projectmanagers can run some bot, only @collaborators can post to #project, @watchers can read #project but not post, while those that are neither @collaborators nor @watchers don't even see the channel... And in #otherproject you can have those same people in totally different groups and with different roles.
Way more customizable than by just having public/private channels and @everyone at your disposal, as Slack does.
And some other features like colours which are nice when you want mods to stand out for public servers, or teams for some sort of competitive event server.