reindeer vs caribou

reindeer and caribou both are nouns.

Word	Noun	Adjective	Verb	Adverb
reindeer	Yes	No	No	No
caribou	Yes	No	No	No

As nouns, reindeer and caribou are synonyms defined as:

reindeer and caribou: Arctic deer with large antlers in both sexes; called `reindeer' in Eurasia and `caribou' in North America

Other synonyms of reindeer include Greenland caribou, Rangifer tarandus.

reindeer (noun)	caribou (noun)
Arctic deer with large antlers in both sexes; called `reindeer' in Eurasia and `caribou' in North America	Arctic deer with large antlers in both sexes; called `reindeer' in Eurasia and `caribou' in North America