Question

deligation is essential for management but decentralization is optional.

Answer 1

Delegation-is passing authority down the organisational hierarchy:gives seniors more time to focus on important strategic roles

Decentralisation- decision-making powers are passed down the organisation to empower the subordinates and regional/product managers

Answer 2

deligation is nothing but pasing the responsibilities from the supirior to the subordinates. here everyone in the organisation has some responsibility.
where as in decentralisation the responsibility is totaly distributed and the manager has no work to do.