Answer:
The executive can veto legislative acts and, in turn, a supermajority of lawmakers may override the veto. The veto is generally derived from the British tradition of royal assent in which an act of parliament can only be enacted with the assent of the monarch.
The president has a fixed term of office. Elections are held at regular times and cannot be triggered by a vote of confidence or other parliamentary procedures, although in some countries there is an exception which provides for the removal of a president who is found to have broken a law.
The executive branch is unipersonal. Members of the cabinet serve at the pleasure of the president and must carry out the policies of the executive and legislative branches. Cabinet ministers or executive departmental chiefs are not members of the legislature. However, presidential systems often need legislative approval of executive nominations to the cabinet, judiciary, and various lower governmental posts. A president generally can direct members of the cabinet, military, or any officer or employee of the executive branch, but cannot direct or dismiss judges.
The president can often pardon or commute sentences of convicted criminals.