You. can pick out a color and have it mixed in different levels. Enamel, urethane, and probably 2-3 levels in base clear for the same paint company. The pigment(color) is the same. You pay the $$$ for the binder. That determines type (enamel, urethane ......) Straight enamel is the cheapest. The high end base coats are for matching new car colors in collision work. Meaning they spend a lot of $$$ on color matches. You don’t need that for an all over. On the other hand, the solid content on more expensive paints is higher. Meaning they cover better. This can be fixed by using a good color primer or sealer under the paint. For example, don’t paint red over black. It takes a lot more coats to cover than over a light sealer for that color. A decent paint store should be able to explain the difference and cost levels. If not, go somewhere else.