Nobile is more bitter with the bit of herbs in it, and tends towards the formal side. Bowling Green is more citric and piney; I think more refreshing.
Both are pretty natural smelling IMHO. Nobile has more depth to it with the addition of the ambery notes ... but sometimes the herbs come out like pencil shavings on me (it happens with Vintage Greenbriar as well).
Bowling Green's duration isn't all that great on my skin, and I think they could have added a bit more spice to make it a really great scent. Bowling Green does remind me of Christmas (I know I'm not the only one on the board to make this statement), probably due to the pine notes.
Personally, I wear Nobile, however my fiancee absolutely loves Bowling Green and used to hunt it out of my collection like a prized game (until she found Happy for Men.)