belching vs reflex action

belching and reflex action both are nouns.

Word	Noun	Adjective	Verb	Adverb
belching	Yes	No	No	No
reflex action	Yes	No	No	No

As nouns, reflex action is a hypernym of belching; that is, reflex action is a word with a broader meaning than belching:

belching: a reflex that expels gas noisily from the stomach through the mouth
reflex action: an automatic instinctive unlearned reaction to a stimulus

belching (noun)	reflex action (noun)
a reflex that expels gas noisily from the stomach through the mouth	an automatic instinctive unlearned reaction to a stimulus
the forceful expulsion of something from inside