inforamtion about datasource

Hi,

We have a NW2004s with ABAP and JAVA installation.

Now while going through the SAP help i came across the following terms as user store

http://help.sap.com/saphelp_nw04s/helpdata/en/5a/a75742b6081053e10000000a155106/frameset.htm

User Data Synchronization

Please see the figure in this context

A)J2EE Engine Database

B)Database of the AS Java

C) User management of the AS ABAP

D)R/3 database

Are this all releated ,if yes how.

Best Regards

Manoj