bird-footed dinosaur vs theropod dinosaur

bird-footed dinosaur and theropod dinosaur both are nouns.

Word	Noun	Adjective	Verb	Adverb
bird-footed dinosaur	Yes	No	No	No
theropod dinosaur	Yes	No	No	No

As nouns, bird-footed dinosaur and theropod dinosaur are synonyms defined as:

bird-footed dinosaur and theropod dinosaur: any of numerous carnivorous dinosaurs of the Triassic to Cretaceous with short forelimbs that walked or ran on strong hind legs

Other synonyms of bird-footed dinosaur include theropod.

bird-footed dinosaur (noun)	theropod dinosaur (noun)
any of numerous carnivorous dinosaurs of the Triassic to Cretaceous with short forelimbs that walked or ran on strong hind legs	any of numerous carnivorous dinosaurs of the Triassic to Cretaceous with short forelimbs that walked or ran on strong hind legs