Can you survive in the desert longer than in the Arctic?

Assuming you packed appropriate clothing and equipment for the environment you are visiting, and did a bit of basic research on survival techniques for the environment you are in, then survival in these environments is entirely possible.

There are primary things you need to take care of to survive in any environment:

• Shelter
• Food & Water
• Fire

Snowy climates (often thought to be separate to a true arctic wasteland climate):

• Shelter can be made by digging snow holes etc
• Water can be readily made be melting snow
• Food is available, such as ice hole fishing local mammals etc
• Fire, most typical snowy areas also have trees

Desert climates:

• Shelter, true deserts are barren open places with little shelter readily available
• Water is available, but you have to work harder to get it using dew traps or digging down to the water table
• Food again is available, but in less places
• Fire, deserts by nature have little in the way of trees or foliage to burn.

So on balance with the appropriate clothing and equipment, I'd say it would be easier to survive in a snowy area like a Canadian winter, than it would be to survive in an area like the Sahara