Snow button does what?
 

On an LS 460, rear wheel drive, what does the snow mode do when i press that button. Does it lock the rear differential and make it like positraction. Or limit the wheel slip by auto braking the wheel that is spinning. Or does the traction control button do this?
I'm trying to figure out if I buy a 460/500 with rear drive and live in Iowa, will i have a problem slipping around in the snow in Iowa?