The B-29 could carry 20,000 pounds of bombs internally compared with 14,000 pounds for the Lancaster.
Supposedly there was a modification that allowed a B-29 to carry two of the British 22,000-pound bombs underwing, just as some Lancs could carry one of the 22,000-pound bombs.
Come to think of it, let's add the 22,000-pound bomb to the wants list!