What exactly do you mean by "help"? If you mean economically/politically, yes, we built up Europe quite a bit with the Marshall Plan, though unlike Japan, Europe retained their own political freedom. Japan was under military occupation for a long time, and MacArthur essentially wrote their constitution for them and made them agree to it.

It boils down to this. At the end of WW2 America realized that the Soviet Union was our next enemy. We did not want the Soviets to start writing checks in Europe and gobble up even more countries so we gave out billions in loans to quickly prop up allied countries. Japan was still very much an enemy in the eyes of most Americans at the time. They received very little aid. In fact, the allies classified millions of Japanese soldiers as "Japanese Surrendered Personal" and used them as slave labor. In Europe the allies where so overwhelmed with the 7.7 million German POWs that they reclassified them as Unarmed Enemy Combatants so they wouldn't have to feed them like POWs. Tens of thousands died.