Impressive work.

I was surprised when I visited Normandy beaches how much damage there still was to the landscape just above the beaches. They sure fought at close quarters on top of the cliff at the south end.

I love the idea, take a photo from exactly the same spot and merge the two.
On the second photo though, the buildings seem to line up fairly well, yet the scale of the people is different when you compare the soldier in front to the man in the colour part. I wonder where they went wrong with that. Maybe they couldn't get the camera position right (or didn't take a photo specifically for this purpose) and used software to manipulate the image to make it seem more correct.

The old photograph was taken from the window of a building, whereas the modern one is at street level. They tilted the old photograph upwards to line up the buildings. If you look in the background the street appears to be going uphill whereas in the foreground there is no indication of any slope.

That makes a lot of sense, There are more photos in the website liked to in the OP as well, you can see where they have tilted things here and there, with building lines and windows not quite lining up. Lovely concept though, worth trying to do perfectly in my opinion, of course you have to be there for that, and may not have access to everywhere required.

I think the sometimes ragged look works as if a curtain in time were torn briefly ....I think the small distortions add to the effect.
Do you really square up your cutlery?