Backshift is a deduplicating (variable-sized, content-based blocks), compressing (xz or bz2) backup program. Full saves and incrementals are pretty indistinct other than the amount of data transmitted, somewhat like with "rsync --link-dest" but without the huge number of hardlinks. It also de-duplicates large file content at a granularity of about 2 megabytes on average; there tends to be a unique copy of each file with size less than around 2 megabytes on average.
SynchroDir is a backup and synchronization utility. Each backup is the subject of a recordable "backup project". This feature allows you to save projects corresponding to different computers, servers, external hard drives, USB keys, etc. You can also backup data of computer Y to computer Z from a controlling computer X. Each backup project includes an unlimited number of "jobs". At the end of the backup process, a log file is available. Each job has a source and a destination, each corresponding to a volume or a directory. The volume or directory must be "mounted", either locally or over the network.