Subtraction of one image from another. Used for motion detection and inspection to detect differences between image to be inspected and "perfect" image.

Subtracting previous from current values to obtain a stationary (detrended) time series

the design of a flag as a variation of another flag, either by changing a color, adding or removing a charge, etc. Usually done to indicate a close cultural, historical, or geographic tie. For example, the flag of Italy was differenced from that of France by changing the blue stripe to green.