They are 3 different compounds with different isolation/absorption properties (soft, medium, hard). Use the one that provides the best results for your particular craft, props, flying style, etc.
According to the Zenmuse H3-2D manual:
There are three types of Vibration Absorber,
the White is softest, the Black is hardest, and the Grey is in the
middle. It is recommended to use the White on DJI F450, not use
any on DJI F550, and the DJI PHANTOM can use any type.