Everyone uses both, but there are differences in degree. For some, the arms initially are relatively passive and pulled along by the body turn. But once the hips are open a little, the arms still have to fire through to get good power. Some do this subconsiously though, and have a "feel" of the arms just naturally following the pivot, not initiating anything on their own.
Zach Johson is a good example of a guy whose swing is driven initially by the pivot, and also interesting because he also has minimal turn of his hands. The hands and arms turn some into the ball, but only until the left wrist is flat and the arms have caught up with the body, basically until the butt of the club is essentially alligned with the belly button. From there, the arms only continue to move with the body, until late, only at the top of his follow through:
I think Lee Westwood is at the other extreme, the arms seperate from the body much earlier, the butt of the club has caught up to the belly even before impact, and then the hands roll over shortly after impact: