While I could probably make a detailed list of every little difference, the fact is there one massive difference while the rest are fairly minute, and that is that in powerlifting you must squat, bench press, and deadlift. Outside of that, depending on goals and programming, powerlifting and bodybuilding training overlap more than most realize, or at least it should. My belief is that most powerlifters do not do enough bodybuilding, and most bodybuilders do not do enough powerlifter. The fact is that to be well rounded in strength and muscle growth, it requires a little bit of both, and the amount of time spent in each phase would be dependent on goals. As mentioned though, powerlifters must squat, bench press, and deadlift as that is what we compete in, whereas bodybuilders do have not any particular exercise they must perform. Typically people think of bodybuilding as reps of 8-12 and powerlifting as reps of 1-3, but that a vast generalization and if either is properly programmed, it will include a little bit of the other. The old school approach to powerlifting to just get as big as possible has seemed to fizzle, and you can go to any competition in the US and pick out a number of competitors who could probably hop on a bodybuilding stage and be competitive with 3-4 months of dieting.
I have actually found the combination of the two to be quite beneficial, especially for bodybuilders post show. The fact is that bodybuilders go through this rut post show where they are slowly gaining weight and usually very unmotivated because of that. Their entire focus is their physique, and after the show they continually are looking worse and worse in comparison to the day of their show, and it plays games with their pysche. What I have found though is that bodybuilders seem to really enjoy transitioning straight into a powerlifting meet prep post show, as this takes the focus off their physique and places it on strength. Also within the phasic structure of training, most likely leading up to their show their were doing very high volume bodybuilding work, so this is also a great time to work into a strength phase.