Caribou is another name for reindeer. These animals are generally referred to as caribou by the people in North America and Greenland and are called reindeer by those living in northern Eurasia.
North American caribou are generally larger than their Eurasian counterparts. Because food is not plentiful in the Arctic, caribou herds must roam great distances in order to survive, particularly during the winter when the majority of the available food is in the form of various lichens.
Eurasian reindeer were domesticated over 2,000 years ago and are still herded by modern residents of northern Eurasia. They are smaller than the caribou of North America.
As of 2014, some scientific doubt exists concerning whether reindeer and caribou are actually the same species. Further research is needed to accurately track the evolutionary journey of these animals.