A king is one kind of ruler but a ruler can be other types also. They can be a queen, a prince, a baron or regent; and some are called a premier, a chairman, or some have been called 'president for life'.
King Arthur
King William I Was a Ruler Of great Britain in The Medieval Times. King William I Was a Ruler Of great Britain in The Medieval Times.
Monarchy.
a ruler and a king.
The emperor
The ruler is the king of the class because another word for king is ruler.
the ruler of England
King Arthur
A king
no they have a ruler, not a king
a king
Zeus is the king and ruler of the Greek gods.
King William I Was a Ruler Of great Britain in The Medieval Times. King William I Was a Ruler Of great Britain in The Medieval Times.
the king was
it is a king
monarch
Arthur was Camelot's king.