tongue tie vs birth defect

tongue tie and birth defect both are nouns.

Word	Noun	Adjective	Verb	Adverb
tongue tie	Yes	No	No	No
birth defect	Yes	No	No	No

As nouns, birth defect is a hypernym of tongue tie; that is, birth defect is a word with a broader meaning than tongue tie:

tongue tie: a congenital anomaly in which the mucous membrane under the tongue is too short limiting the mobility of the tongue
birth defect: a defect that is present at birth

tongue tie (noun)	birth defect (noun)
a congenital anomaly in which the mucous membrane under the tongue is too short limiting the mobility of the tongue	a defect that is present at birth