If they're in breeding plumage, you can tell them buy looking at their scapular feathers. Short Billed will have narrow buffy tips, with the edging extending all the way up the feather. Long billed will have a broader end to the feathers, with the the buffy limited to the tips. I can see people calling the first one you submitted a short billed because there IS some breeding feathers in there, and they have the narrow tips, the buffy edging going all the way up the feather.