Can't see differences between videos?
Use a vector scope and waveform monitor to judge the difference, not your eyes.  Even if you're doing an XOR comparison, there are cases where your eye isn't enough.
Here, for example, I've taken this sample footage from BMD's SDK (available here):
 The original is 12bit RAW.  I then transcoded it to H.265, using these settings:

If I then superimpose the transcoded version over the original, like this:

... and set the blending mode to &quot;difference,&quot; a.k.a., &quot;XOR&quot;

and then use the scopes to analyze the result, you can clearly see that the files are different.

The top half of the above image shows the timeline viewer, and the result of the &quot;difference&quot; comparison.  To the naked eye, it looks black, as if there is no difference.  The bottom half of the above image shows Resolve's waveform monitor.  Here's a detail of that same image:

There's clearly noise at the bottom end of the signal.  Other types of scopes will tell you different information about the comparison.  For instance, you can use a parade to examine Y'CbCr, and see that the transcode operation has affected the image's chroma more than its luma.   
I know that you're trying to examine the difference between files that you've copied and not necessarily transcoded, but this example is meant to demonstrate that scopes can give you insight into the type of difference between the files, when that difference is invisible to the naked eye.