knee jerk vs innate reflex

knee jerk and innate reflex both are nouns.

Word	Noun	Adjective	Verb	Adverb
knee jerk	Yes	No	No	No
innate reflex	Yes	No	No	No

As nouns, innate reflex is a hypernym of knee jerk; that is, innate reflex is a word with a broader meaning than knee jerk:

knee jerk: a reflex extension of the leg resulting from a sharp tap on the patellar tendon
innate reflex: an automatic instinctive unlearned reaction to a stimulus

knee jerk (noun)	innate reflex (noun)
a reflex extension of the leg resulting from a sharp tap on the patellar tendon	an automatic instinctive unlearned reaction to a stimulus