I found a couple of mis-registered 782s that will help explain what can happen if the printing is really out of register.
The first one shows good registration between the brown background, the red color and the yellow color but a very bad mis-registration with the rest.(the outlines and the numbers etc...)

The next picture shows bad mis-registration between the brown background (where you can see that there are non-printed areas for the other colors) and the red and yellow. The outlines and numbers seem to be in place.

You can actually measure how far the brown is far from the red or yellow. How far is the yellow from the red. You can measure how far they are all from the outlines.
This is what I find interesting with screw-ups; they help us understand what is normal and how difficult it is sometimes to make pictures look perfect on a little postage stamp.