belch vs eructation

belch and eructation both are nouns.

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

As nouns, belch and eructation are synonyms defined as:

belch and eructation: a reflex that expels gas noisily from the stomach through the mouth

Other synonyms of belch include belching, burp, burping.

belch (noun)	eructation (noun)
a reflex that expels gas noisily from the stomach through the mouth	a reflex that expels gas noisily from the stomach through the mouth
	(of volcanoes) pouring out fumes or lava (or a deposit so formed)

belch (verb)	eructation (verb)
expel gas from the stomach
become active and spew forth lava and rocks