monarch butterfly vs monarch

monarch butterfly and monarch both are nouns.

Word	Noun	Adjective	Verb	Adverb
monarch butterfly	Yes	No	No	No
monarch	Yes	No	No	No

As nouns, monarch butterfly and monarch are synonyms defined as:

monarch butterfly and monarch: large migratory American butterfly having deep orange wings with black and white markings; the larvae feed on milkweed

Other synonyms of monarch butterfly include Danaus plexippus, milkweed butterfly.

monarch butterfly (noun)	monarch (noun)
large migratory American butterfly having deep orange wings with black and white markings; the larvae feed on milkweed	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