What is the difference between an MRP system and an ERP system? Chapter 1: What is the difference between an MRP system and an ERP system? Each industry uses their own nomenclature but in general MRP and ERP are exactly the same. ERP's are only used for service oriented companies that do not manufacture tangible products. Material requirements planning (MRP) systems are the older materials management system software applications and are used for essentially basic assembly and purchase decisions. ERP systems came about several years later and tied all of a company's geographically distant units together by having one central database to track system inventories. Unlike ERP's, MRP's include a TMS (Transportation Management System) to ensure proper and timely distribution