howl vs emit

howl is a noun but emit is not a noun.

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

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

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

howl (noun)	emit (noun)
a long loud emotional utterance
a loud sustained noise resembling the cry of a hound
the long plaintive cry of a hound or a wolf

howl (verb)	emit (verb)
laugh unrestrainedly and heartily	expel (gases or odors)
make a loud noise, as of wind, water, or vehicles	express audibly; utter sounds (not necessarily words)
emit long loud cries	give off, send forth, or discharge; as of light, heat, or radiation, vapor, etc.
cry loudly, as of animals