I have a Convoy S2+ with the U2 1A that I really like. Found a sale on S2+ with the only difference being it has a U2 1B.
What is the difference in them?
However, it helps to see a color representation from the Ansi spec. Google ANSI white color binning and look at a picture image of what you see on page 7 of spec above, only you see it in color.
The 1A bin will have slightly more red in it than the 1B or another way of looking at it is that the 1B bin will have slightly more green than the 1A.