monarch vs crowned head

monarch and crowned head both are nouns.

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

As nouns, monarch and crowned head are synonyms defined as:

monarch and crowned head: a nation's ruler or head of state usually by hereditary right

Other synonyms of monarch include sovereign.

monarch (noun)	crowned head (noun)
large migratory American butterfly having deep orange wings with black and white markings; the larvae feed on milkweed	a nation's ruler or head of state usually by hereditary right
a nation's ruler or head of state usually by hereditary right