belching vs eructation

belching and eructation both are nouns.

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

As nouns, belching and eructation are synonyms defined as:

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

Other synonyms of belching include belch, burp, burping.

belching (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
the forceful expulsion of something from inside	(of volcanoes) pouring out fumes or lava (or a deposit so formed)