Why do my blue point siamese brothers have different color noses & why does one of them have grey spots on his face & body??

by Jennifer
(Canada)

I have two blue point siamese cats that are 6 years old and I'm wondering why their noses are different colors. One is darker (almost black) & the other is lighter (almost grey). My cat Baby is a little bit smaller since he has had a heart murmur since birth. They are both fixed. My cat Kitty Kitty with the lighter nose also has grey spots mostly on his face and also on his body. Is this from stress? Please help me figure this out!