With SharePoint Designer, you can use three different methods of packaging your sites content:
Backup and Restore, where you create a content migration package (.cmp). Use this method when you need to copy or move an entire site or child site to another server or location.
Export and Import, using Personal Web Packages (.fwp). Use this method to share or reuse a site, list, or library structure. It does not include list items, only the list structure. It can be used to copy files, but only as part of the library structure.
Export a site as a site template. When you use this method, SharePoint Designer does not package the site for you; it opens the browser on the Save Site As Template page. More information on site ...