Discord vs Matrix

Discord follows the same type of interface design popularised by Slack, which is extremely clean and attractive, and doesn't clutter the interface with unnecessary chrome and cruft.

Unlimited amount of users.

Users can invite others to join a Discord channel via a web link, which means no installation is required to use the software - which is one of the big typical barriers to entry for social software.

Discord allows inviting people to a specific channel with a link. Links can be set to expire. Low effort/passive invite mechanics.

You can quickly send invites to people and they can join in using the web client without having to create an account or install the app.

Behaves and looks like Slack for regular text channels, but with the ability to create voice channels as well

Deny access, Deny write message, Allow read messages etc.

Discord provides an API for creating custom bots.

Discord has a wide variety of bots for things from airhorn noises to automated server management, to leveling systems for chat. The bot API is open and there are dedicated sites for finding bots.

Discord shows which game each user is currently playing, which among other things helps users to form PUGs with minimal hassle.

For those that are used to the way Slack (a similar chat client) works, Discord will be familiar in its use, which lowers the learning curve quite a bit for those that have switched or tried Slack before.

The support is limited but still exists. It's a killer feature for dev teams.

Discord prevents users from being DDoSed out of games.

Targeting roles allows for quickly requesting someone from a group e.g. artist, moderator, etc.

Ability to create channel categories for channels to sit inside of.

Free account have no tangible restrictions.
Premium account is just a way to say "thank you" to developers. And it work for all servers of discord (not as in slack). And it can be purchased by one who wants. In contrast to Slask, where all active members of the server should be "premium".

Have localization for many language, including Russian.

Matrix is an open standard, defining simple HTTP APIs so that devs can easily write their own clients, bots, bridges or servers. You're not locked into a specific set of implementations.

Matrix has bridges to IRC (freenode, moznet, oftc, snoonet etc), Slack, Gitter, Rocket.Chat, XMPP, SMS, SIP and others. The point is to 'matrix' all the different networks out there into one single decentralised network.

Riot.im is the easiest way to use Matrix, with great clients for Web, iOS and Android (and Fdroid).

Matrix is decentralized, there's no one central point that the information goes through and so no once central point of failure or control.

Matrix aims to "provide an analogous ecosystem to email - one where you can communicate with pretty much anyone, without caring what app or server they are using" using a neutral identity system.

Matrix is designed to support Instant Messaging, VoIP/WebRTC signalling (voice and video) and Internet of Things communication.

Riot.im includes an app store with integrations for Github, JIRA, Jenkins, Giphy etc - and anyone can add more via Matrix.

Which can be found here.

Matrix is designed to support Instant Messaging, VoIP/WebRTC signalling and Internet of Things communication and allows cross-communication between those services. Meaning one person could be using IRC and another Slack for IMs, or one person could be using Skype and another Google Hangouts for videoconferencing.

Matrix features end-to-end encrypted chats which are syncronized accross all your devices.

E2E is implemented in the matrix-js-sdk library and Riot.im client.