There are many differences between the Articles of Confederation and the US Constitution, but the biggest one is that under the Articles of Confederation the central government was weak and only had a unicameral legislature (which was the main reason why the Founding Fathers created the US Constitution), it didn't had any power to collect taxes or pay international debt, under the Articles of Confederation the US government looked weak on foreign affairs and could not deal with disputes between states because states were the ones who had all the power. Under the US Constitution there is a strong federal government which is divided by three branches: executive, bicameral legislature and judicial with a check and balances system that prevents an abuse of power; the federal government has the power to collect taxes and deal with foreign affairs and disputes between states.