Signal is centralized, closed-source, not-selfhostable (edit: in any meaningful way) and requires being attached to a phone number. (Edit: server source is available, but self-hosting requires recompiling and distributing a custom app to all of your contacts to actually use it.)
Matrix is decentralized, federated, fully open source with multiple client and server implementations, self-hostable, and does not require being attached to a phone number.
Where the metadata goes I think is important as well.
All Signal metadata necessarily goes through Signal’s servers and is tied to your phone number, but not all Matrix metadata ever gets near the Matrix.org if you are using a different homeserver.
I think both are less than ideal in that regard, and I think Briar (strictly P2P) has a much better model for dealing with this at the expense of generally being a UX disaster.
Signal is centralized,
closed-source, not-selfhostable (edit: in any meaningful way) and requires being attached to a phone number. (Edit: server source is available, but self-hosting requires recompiling and distributing a custom app to all of your contacts to actually use it.)Matrix is decentralized, federated, fully open source with multiple client and server implementations, self-hostable, and does not require being attached to a phone number.
Sure, some of those things are accurate (some are accurate-ish). However, there is way more metadata with Matrix than Signal.
To be clear, I use both, but Matrix’ metadata problem bothers me.
Where the metadata goes I think is important as well.
All Signal metadata necessarily goes through Signal’s servers and is tied to your phone number, but not all Matrix metadata ever gets near the Matrix.org if you are using a different homeserver.
I think both are less than ideal in that regard, and I think Briar (strictly P2P) has a much better model for dealing with this at the expense of generally being a UX disaster.