diapsid vs reptile

diapsid and reptile both are nouns.

Word	Noun	Adjective	Verb	Adverb
diapsid	Yes	No	No	No
reptile	Yes	No	No	No

As nouns, reptile is a hypernym of diapsid; that is, reptile is a word with a broader meaning than diapsid:

diapsid: reptile having a pair of openings in the skull behind each eye
reptile: any cold-blooded vertebrate of the class Reptilia including tortoises, turtles, snakes, lizards, alligators, crocodiles, and extinct forms

Other hypernyms of diapsid include reptilian.

diapsid (noun)	reptile (noun)
reptile having a pair of openings in the skull behind each eye	any cold-blooded vertebrate of the class Reptilia including tortoises, turtles, snakes, lizards, alligators, crocodiles, and extinct forms