Matte
No shine at all. The light goes into the colour and stays there, so what you see is the shade itself, flat and deep.
Satin
A soft sheen where the light falls, and the colour darker where it turns away. Pressed pans of every finish take a little of this on top.
Shimmer
Fine flecks through the colour that catch the light one at a time as you move, like a heap of loose powder in a window.
Metallic
Flecks laid close enough that the shade reads as a metal: bright where the light meets it, deep in the shadow.
Each finish is shown on its own pan, in the same daylight.