Need Some Light on Visual Administrator of SAP EP

Dear Gurus,

I know that SDN has lot of Doc on Visual Admin ,still i want the detailed explanation on it. Can any one share with me on

Relation between Visual Admin and

1.User Adminstration..

2.SLD

3.ConfigTool

4.SDM.

5. System Adminstration.

I will be very Great full,

Thanks in Advance,

Phani