Tai Chi is a form of Qigong. Qigong is Tai Chi’s parent. Tai Chi appears to be more deeply rooted in a martial arts tradition, though many people practice it simply for its health benefits.
Qigong is traditionally divided into martial, medical, and spiritual schools. Medical qigong can be further divided into self-applied and external qigong, where an experienced practitioner directs qi into your body, either from nearby or at a distanc.