eructation vs reflex action

eructation and reflex action both are nouns.

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

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

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

eructation (noun)	reflex action (noun)
a reflex that expels gas noisily from the stomach through the mouth	an automatic instinctive unlearned reaction to a stimulus
(of volcanoes) pouring out fumes or lava (or a deposit so formed)