They are the same species, Rangifer tarandus. In Europe and Asia they are called reindeer; in North America, wild ones are called caribou. Domesticated animals are called reindeer everywhere, including in North America — so the split is partly geographical and partly about whether the herd is wild or herded.
The core difference
One animal, two names, divided by geography and domestication rather than biology.
- reindeer — the name used in Europe and Asia, and for domesticated herds anywhere.
- caribou — wild North American populations.
Why it is not a clean split
Because domestication cuts across geography. Herded animals in Alaska are reindeer; wild animals in the same region are caribou. The distinction tracks the relationship with people at least as much as the map.
A detail worth knowing
This is the only deer species in which females regularly grow antlers. Males typically shed theirs in early winter, while females keep theirs through to spring — which has produced the frequently repeated observation that a team of antlered reindeer in December would have to be female.
The words
Reindeer is from Old Norse hreinn, the animal, plus deer — so it is not "rein" as in reins. Caribou comes through French from the Mi'kmaq language.
