Hello Venkanna,
a quick search on SCN shows several answers.
For example: the users are explained under http://support.sap.com/licenseauditing -> Information about SAP System Measurement -> User Classification.
Look around for more information.
(Also, this Discussion probably needs to be moved e.g. to http://scn.sap.com/community/netweaver-as.)
Best regards,
Laszlo