Purchase through AT&T will get you the Gear VR, which works only with the Samsung Galaxy Note 4. You'll also get a carrying case, 16GB microSD card and some other goodies.
The purchase from Samsung's site, however, will nab you the "Innovator Edition" of the Gear VR headset, which looks to include the same hardware and accessories, but includes SDK-level access to developers and people who just can't wait another minute for VR, promising "a host of new content experiences..." for the same price. The choice is yours!
We've had plenty of hands on time with Gear VR, so if you're curious about how it compares to Oculus Rift and Project Morpheus, or if you just want to see what it looks like on our Lily's head, check out our coverage.
Stay tuned for our full review of Samsung Gear VR. In the mean time, here's our hands on.