If you paint, you know that the better quality paint you buy, the higher the pigment load. More bang for the buck, essentially. The most startling difference between brands of the same color is in the second photo, the red chart, third from the left top row is Golden's Fluid Alizarin Crimson, and bottom right is Blick's heavy body Alizarin Crimson. Then there are several where one color name in one brand is essentially the same as a different color name in a different brand.
Like I said at the outset ~ an enlightening exercise. Have a great weekend! xo