NOTHING! They are all terms used to define the same thing. Basically, they refer to applying a new surface over an existing surface. The existing surface might be a bath, basin, or tiles. The new surface is usually a paint of some sort that is being sprayed on to the existing surface. Over the years, we have come across people using house paints, two pack car paints, industrial paints, and other combinations, to try and re-surface a bathtub. None of these products were ever designed for bathtubs and as a result they tend to eventually fail, some lasting a little longer than others depending on the usage of the bathtub.