Theres a difference: Those set photos are taken by people not working for the production from off the set. When they do scenes that are out in the open, its almost impossible to stop such things. You never see spy shots from a closed set.And nothing gets leaked. With 5,000 people worldwide working on this high profile project you would think that someone may snap a picture of something, including any of the set pieces various companies are working on, but nothing so far. Even with big movies like The Avengers you have pictures of the set leaking out every now and then, and those only shoot for a few months. This goes on for years and years. Quite impressive, I find.