How is parliamentary democracy differs from a presidential democracy?

Answer 1

In parliamentary democracies, the Head of Government is not directly elected by the voters nor elected by an electoral college. Instead, the composition of the government is indirectly determined by the composition of the national or federal legislature - the executive draws its power and depends upon the support of the legislature to govern.

Usually in parliamentary democracies, a Prime Minister, Premier or very rarely a President (like in South Africa) is elected by the national legislature immediately after legislative elections. As such, rather than fighting to win a single national office, political parties and coalitions fight to win more than half of the seats in the national legislature (an overall majority) so as to ensure their preferred candidate for Prime Minister/Premier/President will be elected.

This system also means that an incumbent Head of Government can be removed and replaced - possibly by a candidate from a completely different party, and not necessarily the outgoing Deputy Prime Minister/Vice-President - without the need to call an election, if the balance of power in the legislature changes, though this is rare.

In contrast, in presidential systems, a single man or woman is elected by the public to lead the nation and form a government for a fixed term in office, and can usually only be removed by impeachment, resignation or death. Whereas in parliamentary systems the Head of Government has to resign if he or she loses the support of the legislature, in a presidential system, he or she can continue to govern and lead a government even against a hostile legislature. In presidential systems, the President is usually replaced (in the event of their departure before a scheduled election) by a candidate from a strict line of succession, almost always from the same party. Presidential systems also usually feature fixed-term elections (e.g., every four years), whereas in most parliamentary systems, elections are usually held within a maximum term (e.g., must be held on or any day before the fourth anniversary of the last election as the government desires). Presidents may also have the power of veto over legislatures in presidential systems, whereas in parliamentary systems, the Head of Government's power of veto stems from his or her direct control over the legislature.

Very rarely, countries can have both parliamentary and presidential systems (a semi-presidential system). France is such a country, where the Prime Minister and Cabinet are chosen as in a parliamentary system, but the President is chosen as in a presidential system, and government responsibilities are divided between the two. Usually, when the President also controls the legislature, he or she will be the effective leader of the nation - however, should he or she lose control of the legislature in a legislative election, then unlike in parliamentary systems they will remain in office, but unlike in presidential systems, the opposition will form a government. In those situations, the President is usually relegated to managing the nation's foreign policy only.