Ornithischia vs animal order

Ornithischia and animal order both are nouns.

Word	Noun	Adjective	Verb	Adverb
Ornithischia	Yes	No	No	No
animal order	Yes	No	No	No

As nouns, animal order is a hypernym of Ornithischia; that is, animal order is a word with a broader meaning than Ornithischia:

Ornithischia: extinct terrestrial reptiles having bird-like pelvises: armored dinosaurs (thyreophorans); boneheaded and horned dinosaurs (marginocephalians); duck-billed dinosaurs (euronithopods)
animal order: the order of animals

Ornithischia (noun)	animal order (noun)
extinct terrestrial reptiles having bird-like pelvises: armored dinosaurs (thyreophorans); boneheaded and horned dinosaurs (marginocephalians); duck-billed dinosaurs (euronithopods)	the order of animals