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How do presidential and parliamentary systems differ?

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Frescoed throne room in the palace of King Minos at Knossos, Crete, featuring red walls with painted motifs, a stone throne, benches, and a round basin on the floor. — government Frescoed throne room, palace of King Minos at Knossos, Crete, c. 1700–1400 bce.

Presidential and parliamentary systems differ primarily in the relationship between the executive and legislative branches and the selection of the head of government.

Presidential Systems

In a presidential system, such as that of the United States, the executive and legislative branches are strictly separated. The president is elected independently of the legislature, serves as both head of state and head of government, and holds office for a fixed term regardless of legislative support. Cabinet members are appointed by the president and are responsible to them, not the legislature. Because the executive and legislative branches have separate origins and mandates, deadlocks can occur if the president’s party does not control the legislature.123

Parliamentary Systems

In parliamentary systems, such as the United Kingdom's Westminster model, the executive is drawn from and accountable to the legislature. The head of government (prime minister) is typically the leader of the party or coalition with a majority in parliament. Unlike presidential systems, the cabinet must maintain the support of the legislative majority; if it loses this support, the government may be forced to resign. Consequently, the executive and legislative branches are closely integrated, and the government is responsible for the enactment of legislation.342