With orthographic projection there is no perspective. Two objects which are the same size will appear the same size on screen, no matter how far they are from the camera.
In this case the front and back of a building are the same height. So they are the same height on screen. This makes the back of the building look taller since it is farther away.
In this case the front and back of a building are the same height. So they are the same height on screen. This makes the back of the building look taller since it is farther away.