The differences in the two surfaces are in the way it is applied to a surface and also the finish of the surface.
Resin Bound is where the aggregate is mixed in with the resin itself. It is then hand troweled onto the surface to leave a smooth flat finish with no loose aggregate (gravel). Resin Bound is a permeable porous surface which allows water to drain through.
Resin Bond is where the resin is applied to the surface and the aggregate (gravel) is scattered on to the resin surface. Most of the aggregate bonds with the resin while some aggregate will be loose on the top. When the resin is set any excessive loose gravel can be removed. This surface is not porous.