You know how all the German Shepard guys are always going on about 'European lines'?....this is basically the same thing with German Wirehaired Pointers.
So, out in Germany about 1880-1900 some guys decided to develop a hardy multipurpose hunting dog. It was designed to handle any game (boar, deer, fox, martin, and pretty much all game birds) even though there were other dogs who specialized in certain game, this dog was to be a dog to handle all game. They used different pointers, both Engish style and the rough haired 'Gryphon' style hounds of French origin and local rough coated dogs and developed a breed.
Now, in the UK and to a lesser degree in the USA middle class people got wealthy and thought that owning purebred dogs was a good way to imitiate the aristocrats. They took dogs from all over. This included the wire haired multipurpose hunting and pointing dog described above.
The UK kennel club and USA kennel club looked at a subset of the population and set down a 'breed standard' This is very similar to the standard the germans were using, but it allowed (even encouraged) a slightly different coat color, slightly different size, slightly different coat length, but at it's core it was the same dog.
Okay, here is where USA and UK dog breeding veers off from 'european'
Now, all a pedigree is, is a list of who your parents and grandparents are. A 'purebred' is simply a dog where all ancestors on it's pedigree belong to some group. And that's all the middle class wanted, a piece of paper to show the 'pureness' of their dog, rather than letting the innate quality of the dog stand for itself.
So in the USA and UK your dog can be a crap hunter, ugly, totally not fit the standard, but still be a 'purebred' because his parents were of the same breed, as were there grandparents, etc etc.
This generally means a dog population splits into 3 groups.
Group A is show dog, who cares how it hunts/herds/hounds/ whatever as long as it wins in the ring it gets bred. Group B is a working line, the dogs are judged more on how they do their job. While you don't bring in dogs from other breeds no matter how good they are at the same task you don't worry so much about perfect show appearance and adherence to a written standard. (note, when you have 'trials' that artificially attempt to recreate true working conditions to give 'field titles' pretty quick
Group B turns out just like Group A...people breed to win the game, not be good hunters. Kind of like how people build raceguns to win shooting championships rather than build the best combat gun to save their life in an attack)
Group C 'a purebred is a purebred' and they will breed any two purebred dogs just to attach a piece of paper to the dog to allow them to sell it to ignorant consumers who for some reason think 'purebred' is a stamp of quality.
Now, the German or European method is different. Their dogs are 'registered' with the breed club, and registry often requires the dog pass some kind of test. This means a male champion and female champion give birth to a litter of pups, the dogs aren't immediately registered. They grow up a bit and they are tested somehow. If they pass the test they are registered as part of the breed. If they fail the test they can retake it ONCE, second failure means they are out. Just because you have great parents doesn't give you a pass. This means the european system gives some minimal guarantee of quality. If a dog isn't registered because it fails, then any puppies it has are also unregister-able. This may be 'throwing the baby out with the bath water' but it does mean that the average dog registered after passing a test is of at least a certain mimium quality.
This is what the Drahtaar dogs are. They are basically a reimporation of the German Wire haired Pointer from the same source population but they differ in two aspects. #1 they have an inch or two different height requirement, slight color difference, slight coat length difference. #2 the dogs must prove themselves as adequate hunters before being registered.
This basically means on a scale of 1-100 for hunting ability, a purebred German Wirehaired Pointer (GWP) can be anywhere from 1-100 on that scale. Because of the trials, the Drahtaar eliminate those who don't at least rate 50. Your chances of getting a 90 to 100 are still very low from either group, but your chances of getting a real poor hunter are drastically reduced with the Drahtaar.
Of course most 'working' lines of GWPs are going to only breed their top dogs so realistically you will get very similar performance between a top breeder of working GWPs and Drahtaars. What you eliminate is the chance of getting a breeder who talks a good game but breeds lower quality dogs, or a guy who passes dogs off as working lines or show lines based on who is asking (and generally has dogs that fail at both) etc etc.
Now, be aware that whenever you have something that is a 'stamp of quality' people will try and imitate that stamp. A lot of guys who churn out GWPs who can't pass as show dogs try and say 'oh these are working lines, that's why they are the wrong color and wrong size'..but the dogs don't work well either. These same guys are now advertising their GWPs as Drahtaars. If you want to buy a Drahtaar, ask to see registration documentation, NOT breeding pedigrees, or basically ask to see the test results of the mom and dad to make sure they actually passed and aren't GWPs who are simply being called Drahtaars.
Of course, the truth is Drahtaars in Germany are diverting from Drahtaars in the USA simply because of different hunting restrictions. In germany a dog that is an excellent bird dog but can't hunt fox, deer, boar, martin, or whatever worth a damn is out of the program. In the USA if the dog is a good bird hunter that's pretty much all anyone knows, few guys are taking their Drahtaars out hunting mountain lion or feral hog or bear.