Replicache's creator Aaron has a pretty good Twitter thread explaining the difference among Replicache, WebSocket and (classic) CRDTs. I will summarize briefly here:
- WebSocket (and Phoenix Channel) is just a communication method. To maintain consistency and resolve conflict, you need something like Replicache.
- CRDTs are more suitable for p2p scenario while Replicache works better for client-server apps.
- Phoenix's Presence is built with CRDT but it's just a single feature, not a general CRDT toolkit.