There is also a key to finding the differences in the use of yellow. For instance, the first 20 cards in the W515-2 set are awash in yellow. This is really apparent when you lay all of the cards out as I did in the other post about finishing the set. My Aaron Ward is a great example. How can you tell that it's a W515-2 and not a W515-2? You can't look to the borders, which are gone as it is heavily trimmed. But check out the yellow in his shoulders and up the middle of his jersey with the buttons. You don't see that use of yellow in the W515-1s. (Of course the different location of the copyright helps, too!)
I think you can also see that difference in WaJo's cap in the post above. The W515-2 has some yellow in it. Not so the W515-1.