In some systems, a page is simply a container in which content elements ("blocks" or "widgets") are organized. The page might have information attached to it that would be unique for a single web page, such as the aformentioned URL, a TITLE tag, META tags, etc. However, the only managed content on the page would be in the form of assigned content elements.
A CMS that is organized primarily around the concept of pages is sometimes referred to as a page-based CMS. This term is often used perjoratively, meant to imply a limitation as compared to systems that deal with content on a more abstract level.