The discipline called Psychic is one regarding the mind as a whole, and their students are called Psychics at Brakebills. Psychics deal with the area of magic that bends psychic energy with multiple intents. Some divisions inside this discipline are telepathy, mind control and traveling.
Travelers are magicians whose Psychic discipline consists of reading minds and transport themselves (alone or accompanied by others) to different locations inside one plane, or even between planes. It's worth noting that this area of magic is regarded as the most powerful, knowledgeable and dangerous of them all, meaning that the ones possessing it need to have a lot of training to achieve full control.
Astral Projection is considered a branch of traveling, because most travelers bind their body to earth and let their spirit wonder, instead of actually moving body and mind to a different place due to the risk involved with it.