There are 3 kind of avalanche.
A dry snow avalanche which is made up of powdery snow which has an air speed up to 160km.
A dry snow avalanche which is made up of powdery snow which has an air speed up to 160km.
A wet avalanche is a mass of wet dense snow that moves slower than the dry snow avalanche.
A slab avalanche is an unstable block of solid snow. It breaks loose and split into pieces.