Ok, I did a little digging.
For Red Zeppelin, the only difference is note 43 - the floor tom.
- RZ4 - 16" floor tom (rings like a timpani, sounds really nice to my ear)
- RZ5 - 18" floor tom (lower pitch, more of a thud. Doesn’t ring as much)
Regarding the Black Pearls, in the link provided above, the creator states the following:
The difference is in the snare drums, 4A has a double ply batter snare head and has a less ‘crisp’ sound, a bit lower pitch and a longer duration hit than 4B, it actually has similar character to some electronic snares. 4B is a bit snappier and more traditionally ‘acoustic’ sounding but sometimes 4A sits in a mix better, it all depends on what you’re looking for. Other than that they are identical.
That doesn’t mention 5, so I opened up the sf2 files in an editor.
- 5 is exactly the same as 4b - same snare, but with a 2nd high tom.
- Note 47 on both 4a and 4b is a “tom edge” version of the single high tom.
- Note 47 on 5 is a different tom altogether - tuned to a lower pitch, and “boomier.”
These are all the differences I could see:
Hope this helps someone other than myself.