There was a lot to look for in the Eiffel Tower challenge, so we won't drag our feet getting to the answers. Did anyone notice the horse statue on the left? In the second image its leg is curled around more tightly than it appears in the first. The same can be said for the horse on the right, although in this case the situation has been reversed and the one from the first picture has the curled-up leg.
In the first image, standing right by the horse statue to the left, are two people. In the second image, one of them has disappeared. Now for the final and trickiest difference. All the way underneath the Eiffel Tower, on the left side of the road, there are missing street lamps in the first picture. In the second picture, they're there.