I originally bought Winter Wonderland at Sally's because I had seen swatches of Frosty and thought it would kill my lemming. I should have known better! LOL. They are not as close as I had hoped.
Frosty is more of a white color with a kind of glass fleck to it and Winter Wonderland leans more toward silver and is chalk full of glass flecks.
Here is a bottle pick of both:
Once you see the two together, you can really see the difference:
I think I prefer Frosty, but they're a close tie. Don't forget to click on the picks for a larger view.
Thanks for looking!