The version 2 of the navigation data has a lot of approvements when you compare it to the version 1.
The main thing of it is that it is possible to make curved taxiways.
Also a lot of different lights can be assigned to the runways and taxiways.

What also is included is the possibility of making signs beside the taxiways. These signs will also be included in version 2.

One important thing about version 2 is that it is compatible with X-Plane 8.5 and higher.
If you have X-Plane 8.4 or more previous than you should download navigation data version 1.