Which Scaup?

[SANe]

I have several files of this duck. iBird identified one as a LESSER Scaup (Image _65A3032-2) and one as a GREATER Scaup (Image _65A3035-2), each with over 80% confidence. Lesser Scaup are more common in the area (Southern California), but this bird does not have the little "bump" on the head that I typically associate with Lesser Scaup. Hence, I submitted to iBird to see what guidance i could get. No help, sorry to say.  These two photos were taken in Borego Springs, CA, at a pond on a resort golf course that is not currently in use and is now home to many migrating duck species.  Both are the same bird, and images were taken within 5 minutes of each other around 7:10 AM on 2/24/22. So .... Forum members: what is your call?????

[The Bird Nuts]

Lesser.

Edited February 26, 2022 by The Bird Nuts

[Sneat]

Agree with Lesser Scaup

[RobinHood]

Lesser for sure.

[millipede]

The shape of the head can often help but, all ducks(all birds even) can raise and lower feathers changing what we see...  so it's not always 100% reliable. 
The scaups are a pain... it's a little easier when you have decent photos and these give us good views.
For me(not an expert) the "nail"(black at the tip) on the bill is too small to point to greater.
That's about all I can say about it though.

[Charlie Spencer]

Great photos,  whatever they are.