The Lytro images have a lot more data in them (although probably fewer pixels). You can move around slightly in a Lytro photo because it samples light from all directions. Also, Google's version doesn't seem to use the multiple exposures in the final photo. It only uses them to determine which pixels to blur in the first photo, and uses normal gaussian blur instead of simulating a lens.

It does simulate the lens, it says so in the article

Oh... well it doesn't do a very good job. The last example has her hair blurred where it should be sharp. That's not very lens-like.

Yeah, in the first example too (hair at the bottom). But it's still much better than Gaussian blur...

This doesn't capture the whole light field, which is the advantage of a light field camera. Changing the focus is just a fun application if you have access to the whole light field. http://en.wikipedia.org/wiki/Light_field