This is a good question. What Marc08EX has said is what the marketing will tell you. What is actually in the products - well that is another question entirely! Unlike a great many other products, there is no accepted 'normal' so there are a great number of variants out there. Indeed, some QDs and waterless washes will be identical. Some will be weak surfactant solutions, some will have silicones, some will have waxes. A lot of care is necessary because not all of these products offer protection from damage caused by soiling being pulled over the surface. This is one product area where the proof of the pudding is really really in the eating of it!