theropod dinosaur vs bird-footed dinosaur

theropod dinosaur and bird-footed dinosaur both are nouns.

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

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

theropod dinosaur and bird-footed 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 theropod dinosaur include theropod.

theropod dinosaur (noun)	bird-footed 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