scaup help

[sbruenjes]

I saw these birds this past Friday at Raritan Bay in Middlesex, NJ, on the Jersey Shore. This is really the first time I have seen scaup, and there were a lot.. I'm trying to use head shape to understand how to ID greater vs lesser scaup. In the first pic, are the two male scaup facing left near the front greater scaup, and the bird in the back a lesser scaup?

In the second pic, the birds in the center, the male on the right greater, the others lesser? 

Any help would be greatly appreciated.

 

[Tony Leukering]

The definitive IDs I see are indicated. Too many of the birds are angled enough away from profile as to make ID uncertain.