Or how about the difference on the back of these two chickadees?

I found two more photos showing the back of two different chickadees. One bird has more white streaks on its bakc than the other.

http://eileeninmd.smugmug.com/Nature/My-Birdcam-photos/15191804_X2bUH#1157272205_YCsqo-A-LB

http://eileeninmd.smugmug.com/Nature/My-Birdcam-photos/15191804_X2bUH#1157270182_AVNE6-A-LB

I have a couple thousand or more of birdcam photos to go thru. 

Eileen 
Prettyoby