The ‘materials found’ are really what make the difference here. The more expensive model has a radiused fretboard which means the fretboard has a slight curve. This will make playing easier for some. On a guitar, playing barres are easier with a curved board.
However, at least for me, I found the skinny neck of a banjo always pretty easy to barre (I have never played a curved banjo neck) so I don’t know how big a deal that is. It costs more to make a curved neck (just more labor involved).
The big difference is the tone ring. The OB model has a bronze cast ring, like a Gibson Mastertone. The BG model has a hoop which, in Gibson parlance, is known as a sub Mastertone (I have a Gibson hoop Style 11). The tone ring adds a lot of weight but will give you more power and volume, possibly better tone. The tone part is debatable though when you’re talking modern banjos, hoop banjos tend to not use the same quality of materials than tone ring models. But hoop banjos can sound from pretty good to fantastic (just ask Robbie Boone about his style 11). If you plan to do a lot of jamming with loud players, a tone ring banjo might be a better choice though.
(Yay, I got my avatar back. I reduced the size of my pic to 90x90 and it worked.)