Difference Between User Exit and Customer Exit in SAP ABAP Enhancements.

The Enhancement Concept allows us to add our own functionality to SAP's standard applications. It allows to  create specific programs, screens and menus. There are two main types of enhancement, such as user exit and customer exit.

USER EXIT

• Implemented in the form of Sub routine.
• Accessibility to all data in case of perform.
• It is often considered to be a modification instead of enhancement.
• Looses changes in case of upgrades.
• Access key required

CUSTOMER EXIT

• Implemented as function exit: Screen exit, Menu exit, Field exit
• Limited access to data only to import, export, altering and tables parameter of function module.
• It is truly categorized as an enhancement.
• It successfully overcomes the shortcomings of user exits.
• No need of access key.

Key difference between user exit and customer exit

Read : Streamline your SAP landscapes with SAP ABAP enhancements