Friction is defined as the force that opposes the motion of a solid object over another. The sliding friction and static frictions are a type of friction.
Sliding friction – Sliding friction is defined as the resistance that is created between any two objects when they are sliding against each other.
Static friction – Static friction is defined as the frictional force that acts between the surfaces when they are at rest with respect to each other.
For a given two surface, sliding friction is slightly lesser than that of the static friction because it is easy to move the object which already in motion than the object which is at rest.