bellow vs emit

bellow is a noun but emit is not a noun.

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

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

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

bellow (noun)	emit (noun)
a very loud utterance (like the sound of an animal)

bellow (verb)	emit (verb)
shout loudly and without restraint	expel (gases or odors)
make a loud noise, as of animal	express audibly; utter sounds (not necessarily words)
	give off, send forth, or discharge; as of light, heat, or radiation, vapor, etc.