A site is a WIndows SharePoint Services grouping for collaboration which can
contain lists, libraries, sub-sites, and workspaces, allows for users to be
added and removed and have permissions set, and can use templates and
definitions to change the appearance and functionality. A workspace  is a
specialized type of site with functionality tailored around either a single
document (a document  workspace) or a scheduled meeting (a meeting workspace). A
document library  is a specialized list with functionality tailored to managing
documents.