What's the difference between shifting and moving back?

The result is the same. The shift lens is used for 135 and 120 cameras. Because the fuselage is fixed. Moving the axis on the back is the most typical function of a large-format camera.

Compared with the two, it is better to move the shaft backward, which has greater freedom, but it is more difficult to control. Very demanding for photographers! It's a model for professional photography.