The main difference between a parliamentary and presidential system of government is that in a presidential system, the president is separate from the legislative body, but in a parliamentary system, the chief executive, such as a prime minister, is part of the legislative body, or parliament. A presidential system separates the executive and legislative functions of the government and provides what are commonly called checks and balances to limit the power of both the chief executive and the legislature. In a parliamentary system, the legislature holds the power, and the chief executive must answer to the legislature. Another main difference is that in a presidential system, the chief executive and members of the legislature are elected separately by the people, but in a parliamentary system, the legislature is elected by the people and then must appoint or recommend for appointment one of its members to be the chief executive.
Many forms of government are used by countries around the world, and very few governments are completely alike, even if they use the same type of system. Presidential and parliamentary systems of government can vary in specific details from one country to another, but certain general aspects typically are the same in countries that have the same type of system. For example, in some parliamentary systems, the national legislative body is called a parliament, and in others, it might be called by a term such as "national assembly," but they generally serve the same purposes, regardless of their names. Likewise, the specific powers or duties of presidents might vary from country to country, but they generally are all elected by the people and are separate from the legislative body.
In a presidential system, the president is the head of government and the head of state. As the head of government, he or she oversees the operations of the government and fulfills certain duties, such as appointing officials and advisers to help run the government, signing or vetoing laws passed by the legislature and establishing an annual budget. A president's duties as head of state include tasks such as making speeches, representing the country at public events, hosting or visiting diplomats from other countries, and presenting prestigious national awards.
The roles of head of state and head of government often are held by different people in a parliamentary system. For example, a country might have a prime minister who acts as its head of government and a monarch who acts as its head of state. Some countries that have a parliamentary system also have a president instead of a monarch, who acts as the head of state. A country that has both a prime minister and a president is sometimes said to have a semi-presidential system of government, although it is more closely related to a parliamentary system because of the power held by the legislature and prime minister in such a system.
Another difference between these systems of government is the effects that each system has on things such as efficiency and political acrimony. In a presidential system, because the chief executive and members of the legislature are elected separately, it is possible for the president to be from one political party and the legislature to be controlled by a different political party. This can cause discord at the highest levels of the government and make it difficult for the executive and the legislators to achieve their respective goals. In a parliamentary system, the prime minister is almost always from the political party that controls the legislature, so there is less discord, and it is easier for that party to accomplish its goals.
Removing a Chief Executive
Parliamentary and presidential systems also differ in their abilities to remove the chief executive from power. In a parliamentary system, it is much easier for the legislature to remove the prime minister. Even a disagreement in policy or a lack of effective leadership could be enough reason for this to happen. A president is more difficult to remove from his or her position, and it usually is possible only in extreme cases, such as when the leader is accused of a serious crime.