Site Builder is the newest innovation in vBulletin’s line of site management products. It allows an admin user, with the correct permissions, to change and edit the content and look of their site without logging in to the AdminCP. Where Site Builder deals with the outward facing portion of a site, the AdminCP controls the nuts and bolts of the system.
The Site Builder allows an admin to add various functionalities, dictate what they do, and where they’re placed on the site. It can control how your navigation bar is organized as well as which HTML ads appear in your header, and what the site logo is.
For a more detailed information on what Site Builder does do, go here.
To see a list of available modules that you can use see the Module List.
Everything else is controlled and administered using the AdminCP.