All Tai Chi can be Qigong but not all Qigong can be Tai Chi.
Both Tai Chi and Qigong move blood, energy and breath. The main difference is that when you practice Tai Chi there is a different intention. Since Tai Chi is a Chinese fighting martial art, Tai Chi has a martial application that Qigong does not have.
The four parts to Tai Chi
First you learn to move the legs (and feet) then you learn to move your upper body (arms and hands) then you learn to make the first two parts moveme from the waist and finally you learn to follow these movements with the eyes. The eyes are part of the martial intention of Tai Chi.
Both Tai Chi and Qigong stretch, stimulate and compress the energy that moves through the meridians.
Meridians are energetic channels in the body. They flow inside the body, they are not on the surface and they exist in pairs that each correspond to a major organ. Every meridian has many acupuncture points that go along its path.
According to Traditional Chinese medicine meridian paths with their corresponding acupuncture points are responsible for our physical, emotional, and spiritual well-being. As you go deeper into your practice of Qigong and Tai Chi you unblock these channels so the flow of energy can pass freely in your body and you can correct imbalances and areas where the energy may be blocked by moving and stimulating these pathways
This is the main purpose of Qigong and a by-product of playing Tai Chi.
Whether you focus on it or not when you are moving you are stimulating your channels and unblocking the energy.
Meridians run along the arms, legs, hands, and feet and around the body so it is important to get a full body stretch.
Qigong 5 Animals from Wudang, China
There are thousands of Qigong exercises and depending on which area of China you go you will learn different techniques. I train in Wudang, China and we do a stretching Qigong every morning called 5 animals Qigong.
I created a video course to teach this 5 animal Qigong series