Explain the process of regeneration in Planaria

Explain the process of regeneration in Planaria. How is this process different from reproduction ?

Planaria gets cut into many pieces, each piece grows into separate individual, specialized cells proliferate. Mass of cells gets differentiated into various cells and tissues.
Regeneration is not the same as reproduction as most of the organisms would not normally depend on being cut up to be able to reproduce.
(It is normally for repair of the damaged part)