I don't have those two specific colors, but, to my eye, there is enough of a difference in all Kona solids colors to be noticible. Whites can vary quite a bit or just a little and if it's just a little, it can look like one is just grungier than the other. I wouldn't use them together for that reason. Ask Favorite Fabrics if she can check her color card for you to see how close they are.