What is the main difference between federal and confederal systems of government?

The united states uses a federal government. The federal government is granted specific powers by the U. S. Constitution, and any power not granted to the federal government within the Constitution is granted to the states. Therefore the states still retain some level of independence but still are subject to the governance of the federal government. So if the United States were to operate as a confederation, the situation would be reversed, each state would be able to have the power to override federal power as they see fit.

A unitary form of government is one in which political power rests with one central/national government. A confederal form of government in one in which virtually all political power rests with the individual states, and very little with the central/national government. A federal form of government is one in which some political power rests with the national (or federal) government but other, equally important, powers rest with the state governments.