Answer: They have low humidity and low levels of precipitation.
Step-by-step explanation:
Differences: Tundra's are extremely cold, and doesn't get much rain.
Differences: The Dessert is Extremely hot and doesn't get rain.
Explanation: There is already our answer here, If we compare there differences the we will find our answer. This is what I found as the same "doesn't get rain." And we know that precipitation is rain so your answer would be precipitation. Your answer: They have low humidity and low levels of precipitation.