It is well known in the field of Yoga that practice is the main thing that distinguishes Yoga from any other branch of Philosophy. Yoga without practice means Non-Yoga.
However, a wrong knowledge is likely to lead to a wrong practice and can cause delays or accidents. Therefore, the importance of correct knowledge or reasonably correct knowledge cannot be overemphasised.
The Yoga practice happens at various levels or in various perspectives. For example, a Yoga Practice as done in most of the places today deals with physical fitness and health. There is another one that deals with mental fitness and peace. Then there is another one called Mindfulness that deals with harmony, happiness or balance of mind. But, there is an intense practice that is needed for enlightenment or Samadhi state. And, there is the most intense one that is for Spiritual Iberation, called Kaivalya.
When one is considering the gap between Knowledge and Practice i.e. Information and Experience, the gap is smaller when it comes to physical practices. Even in the Physical practices, the knowledge may be insufficient. But, one can imagine that a practitioner knows that he/she has two eyes, one is left and one is right, and then when he/she practices, there is not much doubt about which one is getting used.
When it comes to mental aspects of Yoga, the gap tends to widen. When one practices, it seems like one is doing Physical Practice, and when one talks about information, one is talking about mind, emotions, memory and so on. And, the funny things happen such as prescribing Asana for depression which is caused by a break in relationship!
When it comes to spiritual aspects, the gap is widest and even confused. Now, imaginary things start happening. For example, one is simply seeing some light modifications with eyes closed whereas one thinks that is the enlightenment because the word enlightenment has the word ‘light’ in it. Thus, one is doing a physical practice and imagining in the mind what is spiritual!
In any case, one has to obtain as correct information as possible, understand it as correctly as possible, digest it as correctly as possible and practice as correctly as possible. Some people do only physical yoga for this matter and be happy with it. But, then they should not call it mental or spiritual. Some are doing only spiritual yoga for this matter, but they should not prescribe it for physical illnesses. And, some are not understanding the mental aspects of the situation, which are generally the most profound.
After all, Yoga Deals with Mind more than anything else. Even the traditional yoga states, “yogaH ChittavrutiinirodhaH”. It deals with the mind directly. Any aspect of Yoga Practice must deal with the Mind, to be considered as Yoga!