It would be nice if the program notices if one line is completely displaced which will inevitable lead to all following lines having differences.
Example:
Line 1 of the original is similar to Line 2 of the migrated one, as the migrated one has for some reason one empty line added before the actual beginning. This will lead to as many different lines as the PDF actually has.
This is a bit a hazzle to teach to the program but should be possible. E. g. if a line differs it could be compared to the next line and if that's similar, go on from that point on.