When the air temperature becomes warmer than the freezing point, the snow starts to melt and its water content becomes very high. With this, the delicate snow crystals change into large grains of ice and slush is formed. Slush is basically snow that is starting to melt and thus becomes further wet. People who have had slush puppies (an icy snack) have a better understanding on what the word slush means.
Wet snow is heavier to traverse on than light slow so you will notice how the turns in slush are harder than on softer snow. Similar with crust and crud, more aggressive moves are needed to perform your usual techniques. Smooth carving turns are the way to go in slush if you want to keep it easy and not wear yourself out.

http://carvingup.altervista.org