Please Note: This feature is included with HD Premium accounts.
An Admin account is the account that is used by the account manager.
On the Admin Tab, you can see who has Admin privileges by seeing which account has the gold key next to it.
When the Admin logs in, they also have more Tabs than the Agent's do.
The Admin can give an Agent the ability to have Admin privileges also, by checking the box named "Admin User" in the Agent's properties.