groan vs moan

groan and moan both are nouns.

Word	Noun	Adjective	Verb	Adverb
groan	Yes	No	Yes	No
moan	Yes	No	Yes	No

As nouns, groan and moan are synonyms defined as:

As verbs, groan and moan are synonyms defined as:

groan (noun)	moan (noun)
an utterance expressing pain or disapproval	an utterance expressing pain or disapproval

groan (verb)	moan (verb)
indicate pain, discomfort, or displeasure	indicate pain, discomfort, or displeasure