I just picked up a BD yesterday. Notable differences are the de cocker and night sights. The B can be an ?SA? in the sense that the safety allows it to be safely carried in Condition 1 like a 1911, whereas the BD has a de cocker where the safety would otherwise be. On the BD, because there is no manual safety the only safe way to carry with a round in the chamber is to set the hammer to the safety notch, thus requiring no manipulation of a safety to fire, but requires a stiffer double action pull to fire the first round.