I ordered those 3 sets thinking the same thing you are right now. After reading and comparing closley the sets that hiroboy sells I've concluded this:
Purple is extra coarse (polishing stick C)
the green/white is super fine (polishing stick A)
the 3 stick set has three different grades (polishing stick B):
Green is Fine
Blue is Neutral
Orange is Course
So...
A>B>C from fine to coarse.
If I'm wrong, someone please correct me
HTH,
Steve
NOTE: The review that Laurel wrote used all the sticks from these 3 sets. (at least it seems that way)