The carseats are the same, IMO (which doesn't mean a cover wasn't replaced at any point in time. The things are removable and replaceable).
The reason the black pad is lower in the 2nd pic is because what holds it "up" is the harness straps when tightened around a child. Without the child in the seat, the pad would "slip down" to touch the bottom of the inner carseat seat (its natural position at the lowest harness setting).
In the comparison of the 2 different pictures I think perspective - foreshortening - is at fault. The first has the seat positioned more head-on towards the viewer, and the second is at a much different side-angle. This makes it look like points don't line up when they in fact do IRL.
Another angle:
Here's a video with the seat type in question
http://images.google.com/imgres?img...rg.mozilla:en-US:official&sa=N&start=240&um=1
/not a carseat tech, but faithfully haunting carseat.org since 2003.