The federal government of Mexico is the national government of the United Mexican States, the central government established by its constitution to share sovereignty over the republic with the governments of the 31 individual Mexican states, and to represent such governments before international bodies such as the United Nations. They both have a president and a two-house congress. They both have a state/federal system, wherein the states have governors and their own laws. They both have a written constitution.
Differences: Mexico, until 2000, was ruled by one party for decades. In Mexico, the president is elected for a six-year term (four in the U.S.) and cannot be re-elected. In the United States, the president can be re-elected for a second term.