Difference between .50 calibers.

I’ve always had the question if there’s a difference between the .50 caliber machine guns you see on a fighter plane (P-51 or P-47 for example) and the bolt action .50 rifle. I know that the rifle is built specifically for anti-armor but if a fighter plane uses its .50 it wouldn’t have nearly the same effect. Same caliber should have the same effect, no? Thanks.