Why is their less friction on snow than a concrete path

Because the pressure of your foot on the surface of snow or ice melts a thin layer of the surface, and the friction is very low through the very thin film of water on the surface.

Hi, There is less friction on snow (a porous semisolid), due to friction is strongest on the most solidest (Concrete path) substance, so it would be strongest on a solid, then a semisolid, then a liquid, then a gas