In Nigeria, the President is elected by popular vote, and is the head of state, head of government, and the leader of the Executive branch of government.
In South Africa, the President is elected by the Parliament, and is the head of state and the head of government.
Using this information, you can tell that Nigeria operates as a
and South Africa is a
Unitary State: Confederal State
Presidential Democracy: Parliamentary Democracy
Parliamentary Democracy; Presidential Democracy
Constitutional Democracy: Parliamentary Democracy