How to ignore moved lines in a diff

You may try to sort'em first. Something like:

sort file-a > s-file-a
sort file-b > s-file-b
diff s-file-a s-file-b

Bash (and zsh) can do this in one line with process substitution

diff <(sort file-a) <(sort file-b)

You could do a simple diff, store the result somewhere (to avoid another diff), loop through the lines in either version, then remove those from the other side.

This spawned a separate project for the working code. The code.