In the Beta book, there is Pilot (planetary) and (space), in the beginner game, it is just Pilot, and in Shadows of the Black Sun, it's back to 2 seperate skills. I assume the SotBS is correct, since it's the most recent release, but some clarification on this would be appreciated!
Which skill(s) are to be used for Piloting?
In the Beta, there were two Piloting skills. The Beginner game has some things streamlined for simplicity's sake, and I'd assume two Piloting skills, Pilot (Space) and Pilot (Planet).
The beginner's game states it uses a slightly modified ruleset for the core it will be two skills
As I'm sure you already know, and as they have said before, there are the two seperate skills. Pilot (Space) is for, as I'm sure you guessed, space vehicles, like starships. Pilot (Planetary) is for swoops, walkers, speeders, etc.
There's also another skill. Astrogation. While it isn't directly involved with piloting, it will be very important for a spacer, since it is what you use to calculate Hyperspace jumps!