What model to get?

Im getting a jaguar and I've been thinking of either getting an X-type or S-type
I'm leaning more to the S-type
the only thing that concerns me is that its RWD and the x-type is AWD

I live in Michigan and the AWD would come useful
plus I've never driven a RWD before.
is it really that bad on the snow?
this would be for the wife, so I want her to be safe

The jag traction control is pretty awesome. I have heard of a lot of people using s-types in winter with no problems.
The two cars are totally different. But if it is for your wife and you want to ensure her safety, x will have far better winter handling.

what are the major diff between the two models?

Size, engine, transmission, drivetrain, interior, exterior, wheels, seats, switches, you name it. Best thing for you to do is go drive them both and make a decision.