I'm not 100% sure about this, though.

In general, ski wax can be broken down into two categories: "grip" and "glide."
Glide wax describes a range of waxes which can be applied to nordic skis, alpine skis, and snowboards. The gliding property of a ski is an attempt to optimize the thickness of the thin film of water between the ski and the snow. Skiing over snow is a combination of both wet friction and dry friction — too much water will create "wet drag" (suction) while too little water will result in "dry drag" (friction). A properly selected glide wax will aid in this delicate balance.
Grip wax describes a variety of waxes specific to cross-country skiing with a classical technique. This wax comes in two forms, "kick" and "klister." Kick wax is a firm substance which comes in a small tin. It used for new snow with a clearly-defined crystal structure, and sometimes for older, cold snow (found when the air temperature is below freezing). Klister is a semi-liquid which comes in containers similar to toothpaste tubes. Klister is notoriously sticky and deserves its reputation as a difficult wax to use, but is excellent when used in icy conditions (below freezing, when the snow has lost good crystal structure) or with snow that is relatively warm and wet (above freezing).

http://en.wikipedia.org/wiki/Ski_wax