Snow is certainly not an easy substance to categorize. As kids, we learned that certain types of snow made the perfect snowball and other types that just plain sucked. I'm sure as a skier, you have become more aware of just how variable snow conditions can be. Newly formed snow crystals have sharp points which penetrate into the ski's wax layer and base. As snow ages, its crystals lose thir sharp points and become rounded.
Old snow looks grainy.
It's no longer in its crystaline form and can be moist, water logged, or frozen. As the temperature drops, it forms ice spheres. When a ski travels across the snow, it loses some of its energy to friction. This friction translates into heat which momentarily melts the snow underneath forming a very thin layer of water. This water provides a lubrication reducing the friction between your skis and the snow and, in turn, allowing your skis to run freely across the snow.