One hump or two.

Dromedary, one-hump camels more prevalent in Africa and the Middle East. They are much more common than two hump camels, have a uniform coat of hair and are bad tempered.
Bactrian, two-hump camels are native to the Gobi Desert in Mongolia. They grow a thick coat of hair each winter that falls off every spring. This is to deal with the extreme variation of temperature in the Gobi desert. Bactrian camels are much more mild-mannered.
Due to lower numbers, and the higher regard in the eyes of breeders, Bactrian camels command much higher prices than Dromedary camels.