[sodality2]

I always believed decentralized was if each user doubled as a server and required no external setup (example: scuttlebutt). Whereas federated was a plurality of servers with users communicated with each other but no central authority (email, mastodon, matrix, etc). However, reading some peer to peer literature like that 1500 page behemoth of a book, "Handbook of Peer-to-Peer Networking", it seems they are used relatively interchangeably..

[Arathorn]

the terminology we use in Matrix is:

“federated” = servers can talk to each other; eg email, xmpp, sip, activitypub

“decentralised” = data is replicated between servers; eg matrix rooms are replicated equally between the participating servers; usenet

“distributed” = data is replicated between p2p nodes; eg git, p2p matrix, bittorrent.

[zaik]

Either way it's a lot better than walled-garden style messengers like Telegram or Signal.