I was going to tread myself for Christmas by buying a physical copy of the cool game but am confused on the difference. Is this an updated version of the guide book,
A galactic sandbox RPG set in a Saturday morning cartoon universe · By
Hi! I like to say that TNG is the toolbox, and Voyages is what it can build if you spend 2-3 years and thousands of hours working with it. =) So if you want to create your own Galaxy from scratch then the TNG guidebook is good. If you want to jump straight into almost infinite adventures, then Voyages is for you. They both work well together also.
As far as rules go, Voyages contains a streamlined ruleset that I now vastly prefer. But the original ruleset in the guidebook is solid and works well too.
Hope that helps!