Bee pollen is the assemblage of pollen packets collected by honeybees in a specific area. A screen is placed at the entrance of the hive and the pollen packets on the hind leg of the bees are knocked off and fall into a collection tray. These packets are then placed in a container for sale. Bees tend to go to one type of plant at a time so the different individual packets tend to carry a dominant type of pollen. That results in the packets being different colors. One useful reference to these colors is http://en.wikipedia.org/wiki/Pollen_source.