Difference between an SAP ERP system and DBMS

DBMS or Database Management system is basically the tool/interface required to manage the database.  For example, SQL server or a tool like MYSQL workbench is a DBMS. A DBMS is mainly used by or designed for technical people.

ERP (Enterprise Resource Planning System) is a complete system with one database and number of function modules and has a number of inputs and output interfaces to be used by everyone. For example, there can be a user interface for customer or business people, another for technical people with various skills.

So basically we can say that DBMS can be a subset of ERP.