lunatic vs maniac

lunatic and maniac both are nouns.

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

As nouns, lunatic and maniac are synonyms defined as:

lunatic (noun)	maniac (noun)
an insane person	an insane person
a reckless impetuous irresponsible person	a person who has an obsession with or excessive enthusiasm for something

lunatic (adjective)	maniac (adjective)
insane and believed to be affected by the phases of the moon	wildly disordered