Hello Mr,
The Webex Meeting Site Administration is oriented to manage and access to your Webex Meeting, Events, Training and/or Support.
You can see recorded meetings and also schedule meetings depending of what you need.
On the other hand, webex control hub is the site to manage webes customer account including all services that any customer acquire to any cisco partner. Individual person can also create an account on Webex Control Hub but you can not assign any Cisco webex device to your site because you need to purchase some license to do it.
In summ... Webex Site Administration is accesible for everyone who have a Cisco Webex Account, in contrast, Webex Control Hub is only accesible for Full Admin Users.
