It is not clear whether you are contemplating telling which you have before you or whether you want to know the differences in specification. Suggest you ask a supplier or better still the manufacturer(s). I have K and would have to look closely at how artificial (incandescent) light reflects in the coating from each side - there is some efraction in the coating so it looks a different colour depending on the angle, etc. of the light. That was one thing I noticed at first and would recognise although the effect is much more pronounced on the original "Kappa" forerunner of K.