Cold Backup is possible only when the database is down means it is not available to users to access. Disadvantage is we effort downtime. Here we need to take backup of datafiles, control files, redo files. Here we get consistent backup image.

Hot backup is possible in database open mode means database is available to users while taking backup. Here we need to take backup of datafiles, controls. Here there is no guarantee that backup is consistent.Disadvantage is Excessive redo generation.