Tar does not have any recovery options and, as a result, any error-checking must be manually configured. Dump will skip over any bad sections, and both dump and cpio can end up with significant data loss. BRU archives are portable between any machine that has BRU installed. Lack portability in many instances. BRU can be used to restore previously made archives to any machine that has BRU installed regardless of the filesystem.
Dump is only portable between some systems.
Tar will work on multiple platforms but cannot always be restored to different machines. BRU has the capabilities to backup to multiple media. Multiple volumes should not be used with either dump or cpio. Tar has only introduced support for multi-volume backups in later versions. BRU can backup to multiple media without having to specify the media size and with the only interaction required being that of changing tapes.