grumble vs grouch

grumble and grouch both are nouns.

Word	Noun	Adjective	Verb	Adverb
grumble	Yes	No	Yes	No
grouch	Yes	No	Yes	No

As verbs, grumble and grouch are synonyms defined as:

Other synonyms of grumble include scold.

grumble (noun)	grouch (noun)
a complaint uttered in a low and indistinct tone	a bad-tempered person
a loud low dull continuous noise

grumble (verb)	grouch (verb)
make complaining remarks or noises under one's breath	show one's unhappiness or critical attitude
show one's unhappiness or critical attitude
to utter or emit low dull rumbling sounds
make a low noise