fiend vs succubus

fiend and succubus both are nouns.

Word	Noun	Adjective	Verb	Adverb
fiend	Yes	No	No	No
succubus	Yes	No	No	No

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

fiend: an evil supernatural being
succubus: a female demon believed to have sexual intercourse with sleeping men

Other hyponyms of fiend include incubus, succuba, dibbuk, dybbuk.

fiend (noun)	succubus (noun)
a cruel wicked and inhuman person	a female demon believed to have sexual intercourse with sleeping men
a person motivated by irrational enthusiasm (as for a cause)
an evil supernatural being