lunatic vs pyromaniac

lunatic and pyromaniac both are nouns.

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

As nouns, pyromaniac is a hyponym of lunatic; that is, pyromaniac is a word with a more specific, narrower meaning than lunatic:

Other hyponyms of lunatic include crazy, looney, loony, nutcase, weirdo, bedlamite, madwoman, madman.

lunatic (noun)	pyromaniac (noun)
an insane person	a person with a mania for setting things on fire
a reckless impetuous irresponsible person

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