The base coat, shown in the first two pictures, is the part of the painting process that gives the finish its color. It is applied in several thin coats to ensure full coverage without the risk of sags, runs or drips. The base coat dries to a almost flat finish … but that’s not a problem because the base coat’s sole purpose is to provide the color.
The clear coat, which is applied in a much thicker layer over the base coat, provides not only protection to the base coat underneath, it also provides the gloss or luster of the finish. Compare the third and fourth pictures to the first and second. Same car, same base coat, but a world of difference in the appearance. The difference? The application of the clear coat.
Where the finish was flat and drab with just the base coat, the clear make the paint sparkle like … well … freshly polished silver.