PRESIDENTIAL SYSTEM OR PARLIAMENTARY SYSTEM OF GOVERNMENT?
A presidential system is a system of democratic government where a head of government is also the head of state and leads the executive arm that is separate from the legislative arm. The executive head is elected and often titled "President" and is not responsible to the legislature and cannot, in most cases dismiss the legislature except ceremonially at the end of its tenure. The legislature may have the right, in extreme cases, to dismiss the executive, often through process of impeachment.
A parliamentary system
is a system of democratic governance of a state in which the executive arm derives its democratic legitimacy from, and is held accountable to, the legislature; the executive and legislative arms are thus interconnected. In a parliamentary system, the head of state is normally a different person from the head of government. This is in contrast to a presidential system in a democracy, where the head of state often is also the head of government, and most importantly: the executive arm does not derive its democratic legitimacy from the legislature.