Hi Donny,
I have both, and as others have said , you can’t really compare the 2 programs.
Biab is for creating backing tracks or songs by typing in chord progressions, or even getting it to create it’s own progressions ( I think) , haven’t used it in quite a while, though I did upgrade yesterday.
I used to have it midied to my pa800, ie type in chords biab, the pa800 would then follow the chord progression, I found it a good way of auditioning styles for a song. Used to get some interesting results mixing biab and korg tracks together ie replace a korg guitar track with a biab guitar real track. I like experimenting.

V arranger is a real-time software arranger .
It also has a mode where you can type in chord progressions and create a backing track.
I didn’t actually buy it for its real-time functions , I wanted access to the
ketron and Roland styles it can play and be able to create the midifiles I needed for my style conversions hobby ,for my Korg.