The back lighting makes the Shapes appear more dark from the front side of them and it makes it seem as they have less value. From another angle it makes them seem more brighter as you could see more light on the shapes which makes them seem that they have more value to them
The Side Lighting makes One side of the lighting brighter than the other as shown. one side is lit up and that side has more value and the other has lesser value and is more darker and dim as it does not have light flowing onto it.
The Top lighting illuminates the entire shapes and shows a lot of light which shows a lot of value onto the shapes as well. The Shapes are all well lit and the light is flowing through the entire box to light up the shapes.