Define differentiation?

Define differentiation? Also give details about how can you distinguish between dedifferentiation and redifferentiation?

The cells which are derived from root apical meristem and shoot and other meristem
differentiate and mature to perform specific functions. This act leading to maturation is termed as differentiation. During this, the cells undergo a few major structural changes both in their cell walls and protoplasm.
(i) In plants, the living differentiated cells can regain the capacity to divide mitotically under certain conditions. The sum of events are termed as dedifferentiation. A dedifferentiated tissue can act as meristem, e.g., Interfasicular vascular cambium, cork cambium and wound meristem.
(ii) The product of dedifferentiated cells or tissues which lose the ability to divide are called redifferentiated cells and the term is known as redifferentiation. Secondary xylem and secondary phloem from interfasicular vascular cambium, secondary cortex and cork are the examples of redifferentiated tissues.