Given that two images are similar, how do I find and classify the difference between them?
In order for you to do pairwise difference, you need to do the following:


Generate Ground truth data by drawing bounding boxes on elements you need comparison for and label them i.e if you want to compare text on the hard cover, you need to mark the text region and add a label to it like font type.
Once you have ground truth data, you can then use object detection networks like different variants of Yolo to identify multi class objects in each document.


This should provide you a starting point to solving the problem at hand.