How were the peace plans that ended World War 2 different from the Treaty of Versailles that ended World War 1?

The main difference is that the Axis were left extremely bitter and unable to recover after World War I - They grudgingly surrendered and the unfair treatment of them in the Treaty of Versailles heightened that. They were solely blamed for the war and forced to pay for everyone's reparations, a vast figure impossible for a defeated and destroyed nation to pay.

In contrast, after World War II the Allies were much more fair with the Axis after the war finished; they lent aid and actually helped the defeated nations recover, a far cry from forcing them to pay for reparations on all sides, as was done after WWI. Another aspect is that after WWII ended, there was a new threat to face - Communism. This caused the remaining nations to ally against the oncoming threat, in order to defend themselves.