My lil kiddo has the Rimfrost 2 and I have the Ice 2.
The Rimfrost boots are short, not horrifically short but they will not come all the way up to your knee (they are designed that way). They are CLUNKY, like huge, monsterous, Herman Munster clunky. Very, very stiff most un-bendable, plasticky like boots. Kiddo says they keep her warm and she's happy with them.
My Ice riders are very warm, normal tall boot height and stiff but not uncomfortably so. They are larger than regular tall boots but not horrifically clunky.
Personally, for someone that really rides and is going to be wearing them a lot, the Ice boots are worth paying more $$$. For a small kiddo whose going to bounce around on a pony 1x per week for an hour and stomp through every last puddle and snowdrift she can find at the barn........ the $25 new Rimfrost boots I found on Ebay