From Support

Overview

The RDO Properties Sites are websites which showcase a single listing, whether it be land, commercial, rental, etc. Using the Template Editor, you are able to exercise nearly total control over the way your content appears inside that Site. A single Account (both Manual and Bulk) can hold an unlimited number of Sites, but are charged slightly differently. Any site can hold an unlimited number of Pages, a page can hold unlimited Widgets

To recap, an Account ⇒ Unlimited Sites ⇒ Unlimited Pages ⇒ Unlimited Widgets

The Site/Widget Model

To better understand how Sites fit together, refer to the following diagram: