A site will have its own access control.  You should create a site if you wish to create a venue, where you wish to give only limited users "write" privilege.  At vislab.net, the following information should be published through site:

A page will inherit its parent site's access control.  Any user who has "write" privilege within the site can edit the page.  If you wish to create a page, which any ViSLAB users should be able to edit, you should create a page through  "+Create page" icon at the top of the page.  All except above three types should be published in the form of pages.