crowned head vs emperor

crowned head and emperor both are nouns.

Word	Noun	Adjective	Verb	Adverb
crowned head	Yes	No	No	No
emperor	Yes	No	No	No

As nouns, emperor is a hyponym of crowned head; that is, emperor is a word with a more specific, narrower meaning than crowned head:

Other hyponyms of crowned head include Capetian, Carlovingian, Carolingian, czar, tsar, tzar, king, male monarch, Rex, Merovingian, Shah, Shah of Iran.

crowned head (noun)	emperor (noun)
a nation's ruler or head of state usually by hereditary right	large richly colored butterfly
	large moth of temperate forests of Eurasia having heavily scaled transparent wings
	red table grape of California
	the male ruler of an empire