CHIHUAHUAN DESERT:
The Chihuahuan's distinguishing features are its great diversity of cactus species, and the fact that it's a high-elevation desert. Mostly it occupies a plateau region above 3500 feet in elevation, between the Eastern and Western ranges of the Sierra Madre Mountains. Because of the elevation, winter temperatures in the Chihuahuan can remain below freezing for over seventy hours, and summer temperatures average ten to twenty degrees cooler than in the Sonoran Desert

SONORAN DESERT:
Most of the Sonoran lies below 2000 feet in elevation so in general it's considered "a hot one." Among North American deserts the Sonoran is outstanding for offering the greatest diversity of species.