mbcrowder,
Under OBR, there are 2 "types" of obstruction. Type A which is when a runner is obstructed while a play is being made on him or a BR obstucted before reaching 1B. Under Type A, the ball is immediately dead and the runner is awarded a minimum of 1 base beyond his position at the time of obstruction.
Type B is all other obstuction. Under Type B, the ball remains in play and there is no minimum award.
With regard to balks, under OBR the ball is NOT immediately dead if the pitcher pitches or makes a pick-off throw despite the balk. If all runners advance a base, the balk is disregarded and the play stands.
Also, under OBR, a pitcher is allowed to throw a pick-off to a base from the windup position.
There are over 300 other differences.
Have fun!
JM