What is the difference between “Service Backup” and “User Backup”?
A Service Backup is created by an Administrator and, if scheduled, is run regardless of who the currently logged in user is. A User Backup, if scheduled, will only run if the user that created the backup job is currently logged in.
Service Backups are dependant upon the service application ‘CmdBkSvc.exe’ being started and the Microsoft Task Scheduling service being started.
edit - typo - Ewen