I use avisynth within virtualdub; both free software, and, despite the fact the former is quite hard to understand at the beginning, now I will not live without it!

There is a script that (tries to) detect scene change; after that, you have a list of each version scene change frame numbers, then you could compare them to find out eventual frame discrepancy; but it's not very precise, and it's still better to do it "by hand"!

600ms=15 frames, and probably there are in groups of two or three (usually one at a scene's end, and the other at the beginning of the next one)... I stack the two (or more) versions one above the other(s), then I look for frames differences; even if it's time consuming, it's maybe the faster and more precise way to do it - at least using avisynth.