Made specifically for Final Cut so you don't get the benefits of a general copy tool like Carbon Copy, but you get a lot of flexibility of what you back from a FCP library
I use Carbon Copy for general file backup, but both it and Backups for Final Cut Pro simply make a file-level backup of the library or parts of it. However -- UNIX-family file systems (inc'l HFS+ and APFS) do not have "mandatory" file locking, only advisory locking. For this reason, nothing prevents a "torn write" whereby FCPX is updating the SQLite databases inside the library when the 3rd-party backup utility grabs those pages. In some cases this can produce a damaged library or project. The chance of this seems fairly limited, but my team has seen this happen several times, especially if copying a library on a NAS while another editor has it open in FCPX.
This doesn't happen with the built-in FCPX backup because the app itself knows when it's safe to read the library for backup.
The developer of Backups for Final Cut Pro recommends if you want maximum safety you shut down FCPX when that backup utility runs. The same thing likely applies for Carbon Copy, but unless you have a batch job running CC frequently it's probably not a major risk.