Osteostraci vs animal order

Osteostraci and animal order both are nouns.

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

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

Osteostraci: extinct group of armored fish-like vertebrates; taxonomy is not clear
animal order: the order of animals

Osteostraci (noun)	animal order (noun)
extinct group of armored fish-like vertebrates; taxonomy is not clear	the order of animals