hadrosaur vs ornithischian

hadrosaur and ornithischian both are nouns.

Word	Noun	Adjective	Verb	Adverb
hadrosaur	Yes	No	No	No
ornithischian	Yes	No	No	No

As nouns, ornithischian is a hypernym of hadrosaur; that is, ornithischian is a word with a broader meaning than hadrosaur:

hadrosaur: any of numerous large bipedal ornithischian dinosaurs having a horny duck-like bill and webbed feet; may have been partly aquatic
ornithischian: herbivorous dinosaur with a pelvis like that of a bird

Other hypernyms of hadrosaur include ornithischian dinosaur.

hadrosaur (noun)	ornithischian (noun)
any of numerous large bipedal ornithischian dinosaurs having a horny duck-like bill and webbed feet; may have been partly aquatic	herbivorous dinosaur with a pelvis like that of a bird