What's the difference between normal and reaction force?

Reaction force refers to its physical content - a response to the action of an object. Normal force refers to its direction - it is perpendicular to the surface. Many forces can be normal forces and/or reaction forces, and do not necessarily be both. The elementary physics however often uses the term normal force in a reference to the force produced by a support on an object. In this case it is both a normal (in the general sense described above) and a reaction force.