growl vs emit

growl is a noun but emit is not a noun.

Word	Noun	Adjective	Verb	Adverb
growl	Yes	No	Yes	No
emit	No	No	Yes	No

As verbs, emit is a hypernym of growl; that is, emit is a word with a broader meaning than growl:

Other hypernyms of growl include let loose, let out, utter.

growl (noun)	emit (noun)
the sound of growling (as made by animals)

growl (verb)	emit (verb)
to utter or emit low dull rumbling sounds	expel (gases or odors)
	express audibly; utter sounds (not necessarily words)
	give off, send forth, or discharge; as of light, heat, or radiation, vapor, etc.