grouch vs unpleasant person

grouch and unpleasant person both are nouns.

Word	Noun	Adjective	Verb	Adverb
grouch	Yes	No	Yes	No
unpleasant person	Yes	No	No	No

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

Other hypernyms of grouch include disagreeable person.

grouch (noun)	unpleasant person (noun)
a bad-tempered person	a person who is not pleasant or agreeable

grouch (verb)	unpleasant person (verb)
show one's unhappiness or critical attitude