saurischian vs sauropod

saurischian and sauropod both are nouns.

Word	Noun	Adjective	Verb	Adverb
saurischian	Yes	No	No	No
sauropod	Yes	No	No	No

As nouns, sauropod is a hyponym of saurischian; that is, sauropod is a word with a more specific, narrower meaning than saurischian:

saurischian: herbivorous or carnivorous dinosaur having a three-pronged pelvis like that of a crocodile
sauropod: very large herbivorous dinosaur of the Jurassic and Cretaceous having a small head on a long neck and tail and five-toed limbs; largest known land animal

Other hyponyms of saurischian include sauropod dinosaur, bird-footed dinosaur, theropod, theropod dinosaur.

saurischian (noun)	sauropod (noun)
herbivorous or carnivorous dinosaur having a three-pronged pelvis like that of a crocodile	very large herbivorous dinosaur of the Jurassic and Cretaceous having a small head on a long neck and tail and five-toed limbs; largest known land animal