big weight, small reps work your white muscle fibers...
smaller weight, larger reps work your red muscle fibers.
some of these big lugs at the gym who can nail 450 on the bench once or twice, they struggle doing 225 many times.
now some of us are born with better red muscle fibers and some are born with better white muscle fibers. you probably figured out at some point that you were better as a powerlifter than bb or vice versa. some guys are good at both, some guys suck at both.
however if you work at it you can improve your red or white muscle fibers to a certain extent.
its the same thing with runners. sprinters look very different than marathon runners for a good reason. one is working reds, one is working whites. Manut Bol is fast, but he would struggle running long distance (not saying he could accomplish it but saying he wouldn't get a great time).. he just hasn't trained for that first off, and secondly he probably is genetically made for sprinting.... a long distance Kenyan runner meanwhile would be faster than most doing 400 meters but he wouldn't be as fast as these other guys.