Rangifer caribou vs reindeer

Rangifer caribou and reindeer both are nouns.

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

As nouns, reindeer is a hypernym of Rangifer caribou; that is, reindeer is a word with a broader meaning than Rangifer caribou:

Rangifer caribou: any of several large caribou living in coniferous forests of southern Canada; in some classifications included in the species Rangifer tarandus
reindeer: Arctic deer with large antlers in both sexes; called `reindeer' in Eurasia and `caribou' in North America

Other hypernyms of Rangifer caribou include caribou, Greenland caribou, Rangifer tarandus.

Rangifer caribou (noun)	reindeer (noun)
any of several large caribou living in coniferous forests of southern Canada; in some classifications included in the species Rangifer tarandus	Arctic deer with large antlers in both sexes; called `reindeer' in Eurasia and `caribou' in North America