oxycephaly vs congenital defect

oxycephaly and congenital defect both are nouns.

Word	Noun	Adjective	Verb	Adverb
oxycephaly	Yes	No	No	No
congenital defect	Yes	No	No	No

As nouns, congenital defect is a hypernym of oxycephaly; that is, congenital defect is a word with a broader meaning than oxycephaly:

oxycephaly: a congenital abnormality of the skull; the top of the skull assumes a cone shape
congenital defect: a defect that is present at birth

Other hypernyms of oxycephaly include birth defect, congenital abnormality, congenital anomaly, congenital disorder.

oxycephaly (noun)	congenital defect (noun)
a congenital abnormality of the skull; the top of the skull assumes a cone shape	a defect that is present at birth