King of Great Britain vs king

King of Great Britain and king both are nouns.

Word	Noun	Adjective	Verb	Adverb
King of Great Britain	Yes	No	No	No
king	Yes	No	No	No

As nouns, king is a hypernym of King of Great Britain; that is, king is a word with a broader meaning than King of Great Britain:

Other hypernyms of King of Great Britain include male monarch, Rex.

King of Great Britain (noun)	king (noun)
the sovereign ruler of England when male	(chess) the weakest but the most important piece
	one of the four playing cards in a deck bearing the picture of a king
	a checker that has been moved to the opponent's first row where it is promoted to a piece that is free to move either forward or backward
	a male sovereign; ruler of a kingdom
	a very wealthy or powerful businessman
	a male competitor who holds a preeminent position
	the husband or widower of a queen
	preeminence in a particular category or group or field