what's the difference in the AR vs the SV besides the stowable hood?

There is not much actually, the hood is one, and the cut is a bit different. The sv stands for severe. AR for all around. I have the SV in the fission and honestly I wish I had the AR. Unless you need this as a shell that you will be only using for extreme weather, and mountaineering trips then consider the AR.

Christian:
Can you please explain what makes the AR better than the SV if you do not use it for only extreme wheather? Other than the price of course...
Is the AR more comfortable or what is it?
Thanks.

The SV employs burlier material throughout the jacket. The AR uses a combo of lighter material on the body and heavier stuff on the shoulders/arms/seat.
View Details: Arc'teryx Sidewinder SV Jacket - Men's >