A lot of people don't know about all the different types of German shepherds there are. There are different coat colors with variations as well as different appearances.
There are all-black, bi color (underneath is tan, top black) sable, Luke was a sable,
Zack was a red sable- they are also called Agouti.
There are no WHITE German shepherds.They can only be called White Shepherds because the German Judges have disqualified them from the breed. There are also very very rare panda shepherds and you can find them online.
Black is most desirable for breeding esp. if the parents have the black factor in the lines. It keeps the coat colors very dark and that's desirable to German breeders.

In order below of the photos Luke-sable Ambred; Zack -red sable East German; Kohle black East German working lines and Chili black and tan Ambred. Jet West German Show lines all black coated (long hair).

The following are by 'look'. This occurred when the German wall came down. The dogs that patrolled the wall were desirable dogs to breed to. Very desirable. Kohle was from these lines. Working lines are from East German dogs. [google.com]; "The German Shepherd or Alsatian is a German breed of working dog of medium to large size. The breed was developed by Max von Stephanitz using various traditional German herding dogs from 1899. It was originally bred as a herding dog, for herding sheep."
These are the only type of dog that has had wolf in the lines long ago when Max was breeding-so less than 200 years.

1- is American Bred. Chili, and Luke are typical for Ambreds.They have the weird back legs and slanted back and are bred for obedience titles or show. They haven't had a "German" shepherd added to their breeding program for at least 100 yrs that I know of.
2-is German Bred like Kohle, is from typical East German working lines. Most are bred for working and come from working lines with titles such as Schutzhund I thru III or herding. He has a flat back and stands straight.
3-West German Show lines and I'm afraid Jet is one. He has the slanty rear and is having problems with his front legs as well. I'm not sure how much trouble that will be in his future.
So next time you see a German shepherd you'll understand better why so many look so different.