ABAP/4 Memory

ABAP memory is the memory area that all ABAP programs within the same internal session can access using the EXPORT and IMPORT statements. Data within this area remains intact during a whole sequence of program calls. To pass data to a program which you are calling, the data needs to be placed in ABAP memory before the call is made. The internal session of the called program then replaces that of the calling program. The program called can then read from the ABAP memory. If control is then returned to the program which made the initial call, the same process operates in reverse.

SAP memory  

The SAP memory, otherwise known as the global memory, is available to a user during the entire duration of a terminal session. Its contents are retained across transaction boundaries as well as external and internal sessions. The SET PARAMETER and GET PARAMETER statements allow you to write to, or read from, the SAP memory.  

ABAP/4 memory  

The contents of the ABAP/4 memory are retained only during the lifetime of an external session (see also Organization of Modularization Units). You can retain or pass data across internal sessions. The EXPORT TO MEMORY and IMPORT FROM MEMORY statements allow you to write data to, or read data from, the ABAP memory.