IHW:SC has two space combat systems. One is the main one, used by default for all space combat. The other is Appendix D, an optional Space combat system for small craft - i.e. space ships smaller than 100 tons. 100 tons is the size of the Shuttle, so small is a relative term, but it's smaller than a 747. This system is optional, because it breaks the firm, grounded in science mode of the rest of the game, but it's there if you want to use it.
The difference is the Inertial Capacitor, a squishy device - presumably made from unobtainium - which stores energy used to overcome inertia in straight line flight for use in maneuvering flight. The capacitor is rated at different storage capacities which is inversely proportional to the size of the vessel - thus it's use only in small craft.
The maneuvers use an additive Primitive scheme, where a maneuver consists of a number of "Primitives" - basic maneuvers - strung together, with penalties and energy usage added up. You can string together as many Primitives as you have ranks in the Pilot skill, so that crack pilots can just flat out do more, as well as do it better.
Hopefully this gives folks the proper Star-Wars-y swooshing feel, which is how most people envision space combat with fighters. I prefer the standard system myself, but I wanted folks to have the option. IHW:SC is all about the options, after all.