is there a size difference between the various types of GSD? Say between American Show, German Show, DDR, etc. Thanks
There really shouldn't be much of a size difference as they all should be within the range given by the standard as far as height is concerned.
However, the different types can produce different looks. I generally think of American Showlines being the tallest, of course that may be a trick of the eye because they tend to have higher withers. DDR dogs generally have heavy bone, which can make them look larger than they really are. I have West German Working lines. My males range from 66lbs-93lbs- so there's quite a bit of variation even within lines. I've also seen a lot of variation in German showlines- from nice moderate sized males to dogs that look like Bears. Most of the German Showlines females I've seen have been pretty large.
Some info on lines/types
Breed Types & Related Families
(Types of German Shepherds, by Wildhaus Kennels )