What was the difference between the governments of the Soviet Union, Italy, and Germany?

Soviet Union: The political system of the Soviet Union took place in a federal single-party soviet socialist republic framework which was characterized by the superior role of the Communist Party of the Soviet Union (CPSU), the only party permitted by the Constitution.

Italy: The Government of Italy is in the form of a democratic republic, and was established by a constitution in 1948. It consists of legislative, executive, and judicial subdivisions, as well as a Head of State, or President.

Germany: Germany is a federal parliamentary democracy governed under the Basic Law for the Federal Republic of Germany ("Basic Law"), the Constitution of Germany.