- longer-legged, larger size, and more lanky overall
- longer, thinner bill (especially the tip)
- paler than Eastern; juveniles appear grayish
- less contrast between scapulars and wing coverts than Eastern (does not apply to adults)
Note the long legs, size much larger than the adjacent Greater Yellowlegs, bill shape, grayish coloration, and the degree of contrast between the scaps and coverts.
A different angle of the bill
That is one big, lanky, pale willet.
- more compact shape, averages smaller size
- thicker bill
- darker than Western; juveniles appear brownish-gray
- more noticeable contrast between darker scapulars and paler wing coverts (does not apply to adults)
This photo shows the darker/browner coloration, shorter stature (but tough to see with all that vegetation), and thicker bill.
Here you can get a feel for the bird's smaller size as compared to a Greater Yellowlegs; it is just a bit larger than the GRYE. You can also appreciate the greater contrast between scaps and coverts.
A different angle of the bill, and another view of the darker scapulars and how they contrast more with the paler wing coverts.
If I can get more/better images of these willets in the coming days, I will update this post.