I guess it is up to the person creating the channel. There are “Spaces” and “Rooms”. Spaces are the equivalent of discord “servers”. But rooms can also be created outside of a space, making them similar to a group in Telegram/WhatsApp.

In Element (an app that uses Matrix protocol) you can basically organize yourself as in Discord. Rooms/Servers with subchannels that you can invite people to and distribute admin/mod rights.