Both Uses

contrast
in
The Invisible Man, by Wells
(Edited)

He was struck by the contrast of Mr. Marvel's appearance with this suggestion of opulence.
Chpt 14 *

contrast = difference
Outside the day was bright—by contrast with the brown shadows of the dismal house in which I found myself, dazzlingly bright.
Chpt 23 *

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)