Tai Chi vs. Qigong

What's the difference between Tai Chi and Qigong? Most people have heard of Tai Chi is some way or another. However, not many have ever heard of Qigong. 

Tai Chi is a Martial Art
Tai Chi is, first and foremost, a martial art. Although it has many health benefits, Tai Chi's main purpose is for self-defense. Practicing "Tai Chi for health" is like practicing "boxing for health" or "karate for health" or "wrestling for health". 

Qigong is a Wellness Practice
Qigong is a wellness and health practice specifically for cultivating the body's vital energy known as Qi in Traditional Chinese medicine. It's main purpose is for health and wellness.