How to find the pixel coordinate of difference from the output image got from background subtraction

Question

I have two input images, i have subtracted tow images using background subtraction. How to get the exact coordinates of the difference on the output image? this is the code i m using from geekseek

sub = cv2.subtract(image1, image2)

For e.g background subtraction

how to get the coordinates of Red marked box which is the output of the background subtraction.