What is the difference between delegation and decentralisation of authority?

Delegation is the process by which a manager shares part of their authority and assigns responsibility to a subordinate while remaining accountable. It is a one-to-one relationship between a superior and a subordinate and is essential in every organisation, even a small one. Decentralisation is the systematic delegation of authority throughout all levels of the organisation; it is an organisation-wide policy of pushing decision-making down to lower levels. The key differences are: delegation is a process, while decentralisation is the end result of repeated delegation. Delegation is compulsory because no manager can do everything alone, whereas decentralisation is optional and a matter of management philosophy. In delegation, accountability stays with the delegating superior; in decentralisation, decision-making authority is spread widely. Simply put, decentralisation is delegation extended to the lowest levels across the whole enterprise.