Gotta love diff!
Finding all files and folders that are different in two locations is extremely easy. Using only two parameters we can exhaustively compare two directories, including their sub-directories and produce a list of their differences as such:
diff -qr folder-1/ folder-2/;
-q parameter instructs
diff to print only the files that are different and thus not spam us with thousands of files that are the same.
-r parameter turns on the recursive feature which instructs
diff to check all sub-folders and their files in the two directories under investigation.
diff -qr Desktop/source/ /media/tux/My\ Disk/backup\ A/ Files Desktop/source/Camera/20191023_171328.jpg and /media/tux/My\ Disk/backup\ A/Camera/20191023_171328.jpg differ Files Desktop/source/Camera/VID_20191011_115231.mp4 and /media/tux/My\ Disk/backup\ A/Camera/VID_20191011_115231.mp4 differ diff: /media/xeirwn//media/tux/My\ Disk/backup\ A/Camera/IMG_20191225_165939.jpg: Input/output error