[fixermark]

The oxygen enters the chamber from the permeable membrane that makes up the tank base, and creates a liquid-polymer barrier between the solidifying elements and the bottom of the tank. This means that the work doesn't fuse to the tank bottom, and can therefore be built not in a layered(1) fashion, but continuously. Therefore, both faster and (hypothetically) smoother.

(1) I'm sure there will still be some directional effects in the result---the light is only coming from one direction, for example. But you definitely shouldn't expect to see the "sandwich stacks" effect you get from extrusion-filament 3D printing.