System - a datasource which contains information about how the system is defined. All workstations use this as a bootstrap datasource (defined in their JDE.INI file). Contains OneWorld CNC specific definitions including OCM, Datasource Definitions, Printer Definitions, Security, OMW etc.
Servermap - a datasource that provides information about how the system is defined for server differences. A single servermap is require for each TYPE of server in the configuration. This can be viewed as a "subset" of the System Datasource that contain information that different Operating Systems from a FAT Client requires to connect in their own perspective.
A major difference, which explains why there is one System and different Server Maps is the F98611 - the Datasource Definition. An example is a database datasource for an AS400. The System Datasource would utilize JDBODBC.DLL for its connectivity (going through iSeries Access) - whereas the SAME EXACT datasource for the Server (the AS/400) would use "DBDR" to connect (direct connectivity).
Another example is the OCM. In the J environments, the default BSFN is mapped to the Enterprise Server, and overrides for specific business functions might map certain items to "LOCAL". The server map will ALWAYS run Business Functions "Locally" - so the same J environment mappings might not have any BSFN mappings at all, but would definitely NOT have something mapped to "LOCAL" (which is actually a FAT Client definition, not a server definition).
It is important that the System Tables and Server Map tables look somewhat similar, that they pretty much contain everything the enterprise needs to correctly operate.
In an example customer's site (taken directly from Configuration Planning and Setup) with 1 AS/400 and 1 HP9000 machine, there would be 1 System Datasource, and 2 Server Map datasources (one for the AS/400 and one for the HP9000). If an HP9000 was added to the architecture, a new Server Map would not need to be added - but if a new Intel Application Server is added, then a new server map would have to be created.
Hope that explains it all.