allosaur vs theropod dinosaur

allosaur and theropod dinosaur both are nouns.

Word	Noun	Adjective	Verb	Adverb
allosaur	Yes	No	No	No
theropod dinosaur	Yes	No	No	No

As nouns, theropod dinosaur is a hypernym of allosaur; that is, theropod dinosaur is a word with a broader meaning than allosaur:

allosaur: late Jurassic carnivorous dinosaur; similar to but somewhat smaller than tyrannosaurus
theropod dinosaur: any of numerous carnivorous dinosaurs of the Triassic to Cretaceous with short forelimbs that walked or ran on strong hind legs

Other hypernyms of allosaur include bird-footed dinosaur, theropod.

allosaur (noun)	theropod dinosaur (noun)
late Jurassic carnivorous dinosaur; similar to but somewhat smaller than tyrannosaurus	any of numerous carnivorous dinosaurs of the Triassic to Cretaceous with short forelimbs that walked or ran on strong hind legs