SAP is an ERP (Enterprise Resource Planning) application, which has the capability to integrate the functional processes and data of all departments in any industry. In this application, you can define your procedures, processes, and rules as per your organization, which will enforce every personnel to adhere to the same.
Oracle is a Database Management System (Back end), which is independent of SAP. Oracle is widely used for storing data in a logical manner. Organizations worldwide prefer using SAP as the ERP (Front end) and Oracle (Backend) to store and manage data.
Oracle, like SAP, has its own ERP called Oracle Apps, which has similar functionality to SAP.