What is the difference between chi gung and nei gung?

All chi gung practices are derived from the parent nei gungⁱ systems. The emphasis in nei gung is on developing the core energy that travels through the center of the body, and, from the core, opening and energizing the peripheral energy lines (the acupuncture meridians, for example). Chi gung concentrates on working the more superficial energy lines first, and, through these, affecting the core energy. Today the word chi gung tends to be used to describe all chi development practices. Therefore, although Bruce Frantzis teaches nei gung, he calls it chi gung because this name is more familiar in the West.