Hi Kannan,
I would suggest you to go through SAP Library so that you can understand what exactly the difference is.
MRP and DRP are completely different though both try to create procurement proposals.
You may know SPP is one of SAP's unique breed of product.
Main differences are.
DRP does the net requirement planning which completely rely on the BOD structure where as MRP doesnt have BOD but they do planning according to MRP area, BOD is kind of Location Hierarchy for each Product.
DRP executed in APO but MRP executed in ECC, thus more firm orders are generated in ECC than DRP.
DRP has additional features like Supplier Shutdown, PG procurement, Expedition, Anticipated Demand Coverage, Alerts, Approvals,De expedition of orders which are already created etc which doesnt exist in MRP.
Everything with respect to MRP will be marked with Planning file entry but DRP calculations were saved into BI datasources.
MRP can be directly executed but DRP have to be run in PSM.
BOM structure in DRP will be referred only in KIT TO STOCK process, all other planning is like MTS/PTS process. As it mainly designed for non inhouse manufacturing industries, thus called DRP - Distribution Requirement Planning.
You'll find of lotta diff if you explore yourself.
Regards
Vinoth