The Rift is generally better for seated experiences, the Vive is generally better for room-scale experiences. They are capable of basically all the same things though, at least once Rift gets its Touch controllers.
The Rift has better comfort and convenience features, and is easier to set up. It also costs less in the short run (but adding the Touch controllers should even that out). The Vive comes with its motion controllers though, which means a slew of content that requires motion controllers is available right now, where you'd have to wait for controllers if you got a Rift.