To compare means to examine the similarities or differences between two or more items, ideas, or concepts, highlighting the commonalities or distinctions between them. Contrast refers to identifying and emphasizing the differences between two or more items, ideas, or concepts, focusing on their distinctions.

Contrast is a rhetorical device through which writers identify differences between two subjects, places, persons, things, or ideas. Simply, it is a type of opposition between two objects, highlighted to emphasize their differences.

: to set off in contrast : compare or appraise in respect to differences

It's the difference between the whitest possible white and the darkest possible black. It's measured by displaying a black-and-white checkerboard pattern like the one below and comparing the values.