I would like to point out that "Shetlands" are not the only horse considered to be vastly different from the "foundation origins." (I would also like to say that Boinky has it right... Hackneys are also their own special breed and a Classic Shetland is NO WHERE near what a true Hackney pony is!)
The original Belgian draft horse (from Belgium), looks something like this:
Well, we Americans imported them and selectively bred them, so we have "Belgians" here now that we show and love and they are the most common draft horse in the United States. However, to differentiate, we call these guys "American Belgians" and the older ones above the Belgian Brabant.
This is what we are used to seeing over here:
So you can see... both horses are beautiful but they are vastly different. Here in the U.S. we apparently like to breed for refinement, upheaded presence, and lots of motion. Thus we have the American Saddlebred and such. Both types have their fans, I just wanted to point out that it happens in lots of imported breeds. Even Percherons, Clydesdales, Andalusians, etc. are going to be more refined out here, that's the overall type we seem to breed for. Heck, even dogs.... most dogs are taller and more refined than their European cousins!!!
Andrea