[klabb3]

Sync, continuous backup and transfer are all quite different use-cases.

Most backup/sync products are designed to work in the background and often require upload before download. I don’t know if syncthing does streaming syncs though.

Another difference is transfers can easily be untrusted, as in sender and receiver don’t need access to each others file systems. Take magic wormhole (or email attachments for that matter) as an example.

Taildrop is somewhere in between – I think you have to be on same tail net, but no need for awareness of the other device’s file system.