All lines are the same length in each of the two images in order to allow easy comparison. Click to enlarge image.
One possible explanation I gave for the stubby nose and the starboard (rear) engine protruding more frontward in the "live UA175" is that the plane in the video is actually pointing at a slightly different angle, more towards the camera, such that we are seeing a slightly more frontal view of the plane. This would bring the starboard engine out more and explain the overall foreshortening of the fuselage. However, this still presents a problem with the "live UA175" since this rotation of the plane more frontwards completely throws the angles of the wings off from what we see in this "live" image.
One argument AGAINST this rotation explanation is that if you look at the smaller yellow line, which corresponds to the length of the fuselage from the wings to the tail, it is exactly the same between the flight sim CGI model (top) and the video (CGI model; bottom) plane.
This indicates there actually is not much foreshortening going on at least in the rear part of the plane, and thus argues against the overall foreshortening explanation for the difference in the plane's appearance.
Basically, what we were shown live on TV was a FREAK PLANE.