Just looked it up, definitely not a body builder. Incredible physique? Yes. Bodybuilder? Not even close. I'd estimate he's around 175lbs there. He'd need almost another 80-100lbs of lean muscle mass to be considered a bodybuilder.
Feel free to use your own favorite definitions for words and call Brad Pitt whatever you want... he still spent a ton of time in the gym doing weight exercises, just like a bodybuilder does.
I think usually body builders are associated with insane size which mostly people don't think can be achieved naturally.
But I've had girls tell me that Arnold during his peak in bodybuilding was all natural and that he has superior genetics than everyone else on the planet which helped them achieve that size.
The word you're looking for is athletic.