Turf colorants are comprised mainly of two types pigments and dyes.  Although often the terms are used interchangeably tthere are differences.  Pigments are relatively insoluble and need to be applied as a suspension while dyes are water soluble.   If you handle a pigment you will notice that the stains on your hands, pants and shoes are much more difficult to remove compared to a dye that is more easily washed off.   Interestingly a pigment can be made from a dye using a metallic salt.