The male seems a Lesser Scaup to me, please note:
-just visible peak at rear crown, not rounded (better visible in the thumbnail)
-violett, not green gloss to head
-head seems to small in relation to body for a Greater Scaup.
For the female/1cy I wait for others, so I can learn.
Than thank you BobbitWorm45, I must admit that I have seen Lesser Scaup only in captivity before. So I hope that you can write something more, so I can learn.
I know, the iriscent colour of the head is variable in diving Ducks. Bu while I have seen some Tufted Ducks with a green sheen to the head, Greater Scaup have either green (often) or blue (rare) sheen there. I think violett must be within variation for Greater Scaup, but thats the colour for Lesser Scaup according to literature.
While an ID-book Lesser Scaup has a more peaked crown, I still see a slight peak (yes, just within variation for Greater Scaup).
The flanks are burned out, because of overexposure to this area, but with a little bit of guessing, I see some fine barring there, which is also better for Lesser.
BUT: as said, I like to learn here, and would appreciate more comments. Because, when looking in an european ID-book, I got the impression that the Scaup/Lesser Scaup problem is an easy one, but after reading and learning from some threads here, I realized that this is sometimes not so straightforward.
For me it's the head shape and relative position of the eye in the head, which always seems more closer to the top of the head in greater than lesser. I was also going on the cleaner sides, although I do admit the exposure makes this difficult. I'm sure someone will come along and disagree with me though! i don't mind being wrong.
I had also thought Lesser when I posted it. It was not a particularly favourable light day. The head as I recall is a deep violet almost purple. Here another image of the same group on the same day and location. Hope it helps.