caiman vs crocodilian reptile

caiman and crocodilian reptile both are nouns.

Word	Noun	Adjective	Verb	Adverb
caiman	Yes	No	No	No
crocodilian reptile	Yes	No	No	No

As nouns, crocodilian reptile is a hypernym of caiman; that is, crocodilian reptile is a word with a broader meaning than caiman:

caiman: a semiaquatic reptile of Central and South America that resembles an alligator but has a more heavily armored belly
crocodilian reptile: extant archosaurian reptile

Other hypernyms of caiman include crocodilian.

caiman (noun)	crocodilian reptile (noun)
a semiaquatic reptile of Central and South America that resembles an alligator but has a more heavily armored belly	extant archosaurian reptile