The difference is that you don't have to worry about sanding through as much. With a single stage paint, just color and no clear, the thickness of the color on the car is thicker than on a base coat clear coat, which has a thin layer of color, and more clear on it, for an overall same paint thickness as on a single stage paint car, generally. Of course, there are still wide variations in paint thickness from car to car, but since a car can only have so much paint on it before it will crack from having too much paint, a pure color paint job can have at least twice as much color as a base coat clear coat paint job. That's why I had my 57 Chevy painted with a single color coat and no clear coat, apart from the fact that I don't like clear coat because it makes paint look more glassy and cheap looking IMO, whereas a single color paint properly polished and waxed, looks MUCH richer and deeper than the clearcoat paint jobs.
Single stage paint is also the easiest to touch up or repaint or repair. With base coat clear coat, you have to match the levels of TWO layers on paint for it to look right,but with single color, all you need to do is have the right color match and make the surface sanded down to the same level as the rest. Just look at all the cars on the road with huge patches of clear coat faded off with base color exposed. It looks HORRIBLE. All you can do is repaint.
With single stage paint, you can still polish and buff the paint to look new again, even if its 20 years old, left out in the sun, mostly neglected. Try THAT with a clear coat paint job! Can't do it.
I made 1972 yellow paint look virtually new in 1994, that was waxed maybe once every 5 years before this. Horribly chalky looking to start, but rich color and shine after. Scratched up, true, but at least the color and gloss was still there.
