From the rulebook:
The rules are largely unaltered, but they have been reorganized to make it easier for new players to pick up the basics. The datacards have been completely revamped; now that the miniatures are available, it seemed only reasonable to make the packaging of the mini itself into a fully-functional game aid. The most major alteration is the addition of fleet list rules, which provide guidelines for building fleets as well as many options for weapons and equipment variations. Gone, however, are the various history segments and roleplaying integration rules.