The differences are:<p>* XMPP is using addresses with the same format as e-mail addresses (Jabber ID&#x2F;JID), Signal accounts are bound to your phone number<p>* Signal has strong end-to-end encryption built-in, for XMPP you need OTR or the recent OMEMO port of Signal&#x27;s end-to-end crypto magic<p>* XMPP is federated, where you talk to your server, and it talks to your buddies servers; with Signal everybody talks to WhisperSystems&#x27; servers<p>* XMPP has no decent iOS app, but pretty good multi-device support otherwise