Delegation of authority refers to granting authority by one individual (superior) to another (subordinate). Therefore, its scope is confined to a manager and his immediate subordinate. When we delegate authority, we multiply it by two i.e. the delegator and his subordinate, to whom authority is delegated. Delegation is a process of sharing of task and authority between a manager and his subordinate.
Decentralisation of authority is not restricted to two individuals. It involves systematic delegation of authority at all levels and in all functions of the organisation. In case of decentralisation, managers at middle and lower levels are granted the authority for taking decisions on tasks assigned to them. Therefore, the scope of decentralisation is wider than that of delegation. When we decentralise authority, we multiply it by many.