belch vs emit

belch is a noun but emit is not a noun.

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

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

Other hypernyms of belch include breathe, pass off.

belch (noun)	emit (noun)
a reflex that expels gas noisily from the stomach through the mouth

belch (verb)	emit (verb)
expel gas from the stomach	expel (gases or odors)
become active and spew forth lava and rocks	express audibly; utter sounds (not necessarily words)
	give off, send forth, or discharge; as of light, heat, or radiation, vapor, etc.