fiend vs disagreeable person

fiend and disagreeable person both are nouns.

Word	Noun	Adjective	Verb	Adverb
fiend	Yes	No	No	No
disagreeable person	Yes	No	No	No

As nouns, disagreeable person is a hypernym of fiend; that is, disagreeable person is a word with a broader meaning than fiend:

Other hypernyms of fiend include unpleasant person.

fiend (noun)	disagreeable person (noun)
a cruel wicked and inhuman person	a person who is not pleasant or agreeable
a person motivated by irrational enthusiasm (as for a cause)
an evil supernatural being