On the highest level. Yoga is the same as one between an atman ponmatman.Yoga is a conceptual system that is based on the breaking of the waste. Using the concept of breaking of the waste is applied theory and theory into practice as yoga system.
In the highest level Yoga is a unity between the soul of a Brahmin , yoga is a concept based on the Samkhya. Using the concept of Samkhya theory. The theory is applied practices yoga system.