You can review the wiring diagram posted on the forum of the two systems to see if you can spot the difference that may be feeding the other connector.
The number of speakers is identical between H&K and B&W and my understanding is the difference in wiring is largely driven by the additional microphones and diplexer on the B&W. But there may be more to it.
There are few who do the change over though as from what I've read you're better off going with something else entirely than going B&W if you already have H&K. B&W is a notch above H&K in clarity and depth, but the bass output is pretty much identical. So how much you'll enjoy bumping to B&W from H&K would depend on your listening tastes. But I'm going to say it is not really a worthy upgrade if you already have H&K...
Old thread where people hashed this out:
https://g30.bimmerpost.com/forums/sh....php?t=1512934
G30 Technical Guides thread:
https://g30.bimmerpost.com/forums/sh....php?t=1364915
Wiring Diagram is in #8 G30 Infotainment. I haven't studied it extensively.
The soundstage in my previous car, Mercedes, was a LOT better than the soundstage in the G30 IMHO. The C300 H&K system sounded superb. I'm sure the Burmeister they have in them now as an upgrade are top notch as well. But that's another topic altogether.