megalomania vs psychopathy

megalomania and psychopathy both are nouns.

Word	Noun	Adjective	Verb	Adverb
megalomania	Yes	No	No	No
psychopathy	Yes	No	No	No

As nouns, psychopathy is a hypernym of megalomania; that is, psychopathy is a word with a broader meaning than megalomania:

megalomania: a psychological state characterized by delusions of grandeur
psychopathy: any disease of the mind; the psychological state of someone who has emotional or behavioral problems serious enough to require psychiatric intervention

Other hypernyms of megalomania include mental disease, mental illness.

megalomania (noun)	psychopathy (noun)
a psychological state characterized by delusions of grandeur	any disease of the mind; the psychological state of someone who has emotional or behavioral problems serious enough to require psychiatric intervention