SAP Memory 
SAP memory is a memory area to which all main sessions 
within a SAPgui have access. You can use SAP memory either 
to pass data from one program to another within a session, 
or to pass data from one session to another.  Application 
programs that use SAP memory must do so using SPA/GPA 
parameters (also known as SET/GET parameters). These 
parameters can be set either for a particular user or for a 
particular program using the SET PARAMETER statement. Other 
ABAP programs can then retrieve the set parameters using 
the GET PARAMETER statement. The most frequent use of 
SPA/GPA parameters is to fill input fields on screens 

ABAP/4 Memory 
ABAP memory is a 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.