I think the difference is VW created a program within the vehicle to pass the test, knowing the vehicle would otherwise fail. The others, with the lack of evidence to the contary, passed the test, but are higher in real world driving. Much like saying the bloke who writes the answer to a test on his arm is not more of a cheat than someone who walks into a test chanting a formula they cant remember then writes it down at the first avaliable opportunity.
Much the same as how the sticker on the front of the car tells you the vehicles fuel economy, and in real life this is no where near reality. A lab test is there to set the benchmark in controlled conditions. You pass this without using a computer to sense the test and run the car differently you pass.