The Articles of Confederation was the first written form of government of the United States, under the Articles of Confederation the central government was weak because it's framers were concerned that if they gave power to a central government it would lead to tyranny, but the result was an unstable nation so they created The Constitution on the Constitutional Convention of 1787.
The new Constitution expanded the federal U.S. government by creating three branches of power instead of an unicameral legislature like the Articles of Confederation, the Constitution established an executive power (President), a bicameral legislature (house of representatives and senate), and a judicial power with a system of checks and balances to prevent the abuse of power and allowed one vote per Representative or Senator instead of one vote per state, it also states that the Supreme Court is the judge of disputes between states and that an amendment can be added if three fourths of states agree. The Constitution gave power only to the Congress to lay and collect taxes and removed that power from the states, it also stated that only the federal government has the power to coin money, and removed the unanimous consent to ratification, only 9 states are needed for ratification under the Constitution.
