What specific visual feature is striking on the breeding male Bobolink but not typical of the Red-winged Blackbird male?

Answer

A prominent white rump

The breeding male Bobolink is characterized by a black body offset by a prominent white rump, a buffy nape, and a pale cap, creating a multi-colored patchwork look.

What specific visual feature is striking on the breeding male Bobolink but not typical of the Red-winged Blackbird male?
birdComparisonblackbirdBobolink