groan vs utter

groan is a noun but utter is not a noun.

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

As verbs, utter is a hypernym of groan; that is, utter is a word with a broader meaning than groan:

Other hypernyms of groan include emit, let loose, let out.

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

groan (adjective)	utter (adjective)
	complete and absolute
	without qualification; used informally as (often pejorative) intensifiers

groan (verb)	utter (verb)
indicate pain, discomfort, or displeasure	express in speech
	articulate; either verbally or with a cry, shout, or noise
	express audibly; utter sounds (not necessarily words)
	put into circulation