Open back vs closed back. The 280s are closed back. Great for isolation, for not letting ambient sound interfere with the music. It also changes the way the tr

Open back vs closed back. The 280s are closed back. Great for isolation, for not letting ambient sound interfere with the music. It also changes the way the transducers work, a little bit. The 600s are open back. Obviously there's no isolation, but the transducers work more freely. It's a bit easier to distinguish tiny sounds from a huge background. I've both the 600 and the 280. Great phones both, in different ways.