Parliamentary Democracy is a system of representative government in which the dominant party in the legislature determines the Prime Minister.CIA World Fact Book: United Kingdom This method of government differs from the United States model of representative government whereby the executive has a fixed four-year term and often holds a significant influence over the legislative branches of government. Parliamentary democracies, in theory, make the executive more dependent on the legislature; prime ministers can be changed more frequently, often without an election.
Westminster Model
Citizens elect members to Parliament; the majority party then elects the executive branch. The Prime Minister can be removed by a vote of no confidence from Parliament. In some nations, the hereditary monarch, whose function is primarily ceremonial, may still disband the legislature during time of war. Bills can be introduced by both houses as well as the executive branch, although bills introduced by the executive take precedence. Members of the Parliament are not permitted to introduce either spending bills or tax bills. United Nations Development Programe: Governing Systems and Executive-Legislative Relations
Western European Model
The prime minister or chancellor is chosen from the majority party in the Parliament and can select their own Cabinet with approval by Parliament. The President is selected separately and has relatively weak powers. The legislature can remove the prime minister by the act of dissolving Parliament, but they must select a new executive at the same time. Bills can be introduced by both houses and the executive branch. The President can, without the consent of the legislature, pass decrees with the power of some laws.United Nations Development Programe: Governing Systems and Executive-Legislative Relations
French Hybrid
Elected separately, the President has strong powers and selects his cabinet and prime minister, who presides over Parliament. Parliament can't remove the president but can dissolve the parliament which effectively removes the president and his cabinet. The lower house can be dissolved by the President. Both houses and the executive branch can introduce legislation, but Parliament can't introduce legislation that would impact expenditures. Appointed governmental bodies can make recommendations in regards to possible legislation. Bills that have been introduced by the executive branch take precedence over those by parliament members.United Nations Development Programe: Governing Systems and Executive-Legislative Relations