There is an interesting comparison on Wiki here:
http://en.wikipedia.org/wiki/Maximum...-24_bomb_loads
Bomb load alone doesn't adequately explain what each aircraft type had to carry over what distance. The US Air Force was trying to use precision bombing during daylight and trying to defend their aircraft too and from the target. The RAF had decided night bombing was 'safer' and tended to bomb an area. Those two arguments themselves being gross over simplifications too.