duck-billed dinosaur vs hadrosaur

duck-billed dinosaur and hadrosaur both are nouns.

Word	Noun	Adjective	Verb	Adverb
duck-billed dinosaur	Yes	No	No	No
hadrosaur	Yes	No	No	No

As nouns, duck-billed dinosaur and hadrosaur are synonyms defined as:

duck-billed dinosaur and hadrosaur: any of numerous large bipedal ornithischian dinosaurs having a horny duck-like bill and webbed feet; may have been partly aquatic

Other synonyms of duck-billed dinosaur include hadrosaurus.

duck-billed dinosaur (noun)	hadrosaur (noun)
any of numerous large bipedal ornithischian dinosaurs having a horny duck-like bill and webbed feet; may have been partly aquatic	any of numerous large bipedal ornithischian dinosaurs having a horny duck-like bill and webbed feet; may have been partly aquatic