How do Ultra high performance tires compare with High performance all season tires in the snow?

RL

 

They are usually useless in the snow.

 

I agree so some extent.

Virtually every Z-rated tire is completely useless in the snow.
Most all season tires fall into one of two categories:

1. Great in snow, horrible in the rain and hydroplaning.
2. Marginal in snow, reasonable in the rain and hydroplaning.

Tires need a zig-zag pattern to get good snow grip. But water does not flow very well through such patterns so hydroplaning could be a larger risk on a good snow tire.