Expression is what one normally does under the impulsion of nature. It keeps one tied to groves of habit, in fact, strengthens the tendency through repetition.
Suppression means to holding a movement or energy inside but not expressing it. It is like not expressing the anger or lust that one is feeling very much within. Its possible danger is that the mind may continue indulging and playing with the energy, which can then take deviant routes. If indulged excessively in the mind but not given outward expression, it can disturb and destabilise the system.
Repression is when one is not even aware of the negative movements, which then take either devious acceptance routes or simply block the energy.
Sublimation is a better way in that the suppressed energy takes a creative route through sports or art and literature.
Rejection is to actively reject the movement not only in its outer expression but also from the thoughts and feelings. It is somewhat like emptying the container forcefully by throwing away the wrong movements in their gross as well as subtle forms.
Affectionately,
Alok Da
