It only matters if you actually want to get bigger. If you want to do the same weight and stay the same size for years on end it doesn't matter.
no it doesn't you can lift semi light, go for high reps, switch up some stuff, not lift too heavy, because in the end if you lift like an idiot like branch or ronnie you end up with permanent nerve damage. Bob Chic will tell you lifting heavy has nothing to do with bodybuilding, I think your thinking of power lifting.
Drugs play a much greater role in the bigger and harder look.