SAP is an ERP ( Enterprise Resource Planning) Application, which has the capability to integrate the functional process and data of all the departments in any industry. In this application, you can define your procedures, process, rules as per your organization, which will enforce every personal to adhere to the same.
Oracle is a Database Management System (Back end), which is independant of SAP. Oracle is widely used for storing data in a logical manner. World over organization prefers 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 like SAP.