Smooth - Smooth wheels come with a shiny coating on the riding surface that feels grippy at first, but wears away quickly.
Wide - More traction and stability at high speed so you'll be less likely to slip out of your line.
Hard Line - Hardline wheels come in a conical shape with sharp edges and an extra wide riding surface for maximum grip and control on any terrain.
101a - Most common durometer offering a good balance between speed and grip. Meant for skateparks and other smooth surfaces.