File Sync:
File Sync allows remote file access/sharing from anywhere on all devices
Backup:
Backups are files / folders that aren’t kept in the ”sync folder”
Remotely backup files on your local/users machine.
These files are saved on the server, not in your “sync folder”
Any time the file changes on the local machine, it creates a revision on the server.
You can restore backups from the Web UI under the “Backups” tab. No file access remotely.