Client-side classes and server-side equivalents

Client	Server
ClientContext	SPContext
Site	SPSite
Web	SPWeb
List	SPList
ListItem	SPListItem
Field	SPField

Notice that the SharePoint Foundation 2010 managed client object model uses the same legacy naming pattern for site collections and sites as the server object model. 

The Site class represents site collections, and the Web class represents sites. 

My preference for using these classes is to name the variables so that the variable name indicates whether it is a site collection or a site, even though you must use the Site and Web classes to declare them.

The following example shows how name variables.

C#

ClientContext clientContext = new ClientContext(siteUrl);

Site siteCollection = clientContext.Site;

Web site = clientContext.Web;