lunatic vs moonstruck

lunatic is a noun but moonstruck is not a noun.

Word	Noun	Adjective	Verb	Adverb
lunatic	Yes	Yes	No	No
moonstruck	No	Yes	No	No

As adjectives, lunatic and moonstruck are synonyms defined as:

lunatic and moonstruck: insane and believed to be affected by the phases of the moon

lunatic (noun)	moonstruck (noun)
an insane person
a reckless impetuous irresponsible person

lunatic (adjective)	moonstruck (adjective)
insane and believed to be affected by the phases of the moon	insane and believed to be affected by the phases of the moon