what is the exact difference between regeneration and reproduction ? when reproduction also involves in regeneration cells , hard cells and soft cells, tissues etc, then why regeneration does not occur for growing a hand back after the hand is being lost ?

reproduction always produce new progeny but regeneration can be within organ level, cellular level or tissue level that perform function of healing rather than reproduction . only in special cases like in planeria regeneration is a type of asexual reproduction. in other cases regeneration can not produce new progeny. it only help the organism to recover itself from cell injury