What is the difference between differentiation …

Differentiation: The cells derived from root apical meristem (RAM) and shoot apical meristem (SAM) and cambium differentiate, mature to perform specific functions. This act leading to maturation is termed differentiation. They, undergo a few or major structural changes both in their cell walls and protoplasm.
Dedifferentiation: In plants, the living differentiated cells can regain the capacity to divide mitotically under certain conditions. The sum of events, that bestow this capacity to divide once again, are termed dedifferentiation. A dedifferentiated tissue can act as meristem (e.g., interfascicular vascular cambium, wound meristem, cork cambium).
Redifferentiation: The product of dedifferentiated cells/tissue which lose the ability to divide are called redifferentiate cells/tissues and the event, redifferentiation. However, the growth in plants is open, and even differentiation in plants is open, because, e.g., the same apical meristem cells give rise to xylem phloem, fibres, etc., cells/tissues arising out of same meristem have different structures at maturity. The final structure at maturity of a cell/ tissue arising out of same meristem is determined by the location of the cell within.