Distributed would be peer-to-peer. Decentralized can be client-to-node with no central node. A lot of people use these terms interchangeably and call distribute

Distributed would be peer-to-peer. Decentralized can be client-to-node with no central node. A lot of people use these terms interchangeably and call distributed systems decentralized since distributed systems have no centralization either, but this system with federation is also a valid decentralized system