The US government is the national state of the United States, a constitutional republic of North America, composed of 50 states, a federal district, Washington D.C. (the national capital) and several territories. It is constituted under the theories of separation of powers, checks and balances. The federal state is divided into three separate, divided and separate branches: legislative, executive and judicial, whose powers are conferred by the Constitution of the United States in Congress, the president and the federal courts, respectively. Each branch has an exclusive sphere of its own competence and powers that allow them to limit the actions of the other two branches. The purpose of this system is to avoid the tyranny that would occur if one branch of public power concentrated too much power and dominated the other two. The powers and duties of these branches are defined in more detail by the minutes of the Congress, including the creation of executive departments and courts inferior to the Supreme Court.
What is the difference between the head of government and the head of state? The main difference is that the head of state formally represents the people of the nation, while the head of government is the single person who is the leader or "in charge" of the system of creating and executing laws.