Both Uses

contrast
in
And The Mountains Echoed
(Edited)

She wears a bright yellow coat, buttoned to the throat, which contrasts with the dark gray overcast sky above.
Chpt 6 *

contrasts = differs notably (in brightness or tone)
His jeans were stiff with dirt, and they were too short besides. By contrast, his T-shirt hung almost to his knees.
Chpt 7 *

by contrast = in a comparison that shows differences

Definitions:

(1) (contrast as in: contrast their writing styles)
point to differences between; or compare to show differences
(2) (contrast as in: there is a contrast)
a difference -- especially a notable difference; or the side-x-side arrangement of things that draws attention to an unmissable difference
(3) (contrast as in: sharpen the picture contrast)
the difference between tones of an image -- as in a photo or video -- such as the quality of brightness or the intensity of shades or colors
(4) (meaning too rare to warrant focus)