My WB Kirsten's hair is a lighter color than the golden hair of the Mattel Kirstens (and even the later PMs). Molly's and Sam's hair are lighter for WBs too.

If you go to my website (in my signature) you can see comparison charts of all the dolls PM to Mattel (including a separate column for WB) and see comparison pictures. Just click on whatever doll you want to see to bring up her page of comparisons.

The website is due to be updated soon, so the rest of it is kind of in a shambles, but the comparisons part is fine.