The Green Sandpiper is slightly larger, bulkier, and has longer legs compared to the Common Sandpiper. Its plumage contrasts more distinctly, with darker upperparts and brighter, whitish underparts that are especially noticeable in flight. From above, it has a white rump and a white leading edge on the tail feathers, which align with its dark back and barred tail tip. From below, the dark underside of the wings contrasts sharply with the white body, a feature that sets it apart from the Common Sandpiper, which has less contrast between its wings and body. In spring migration, the Green Sandpiper displays its breeding plumage with deep blackish-brown upperparts marked by fine light barring, compared to the Common Sandpiper’s lighter upperparts with more whitish and beige barring. The Green Sandpiper’s underparts are pure white with some dark markings on the anterior edges of the flanks, while the Common Sandpiper’s flanks are buffy-cream with numerous dark spots. The Green Sandpiper has a darkly streaked head, nape, and upper chest, creating a noticeable ‘breastplate’ effect absent in the Common Sandpiper. It also features a prominent white eye-ring and a subtle whitish supercilium over the black loral area, whereas the Common Sandpiper has a more complete white supercilium and a dark cap. Its legs are greenish, in contrast to the yellow-green legs of the Common Sandpiper. These characteristics remain evident during autumn migration, though the upperparts become slightly more uniform. Chicks are covered in gray-brown down with blackish streaks and white undersides. A black stripe runs from the beak through the eye. Juvenile Green Sandpipers resemble adults in breeding plumage but have more beige spotting on the upperparts and all-white flanks without the dark markings seen in adults.