Windows SharePoint Services are sort of a superset of the FP Server
Extensions. They used to be SharePoint Team Services, which is also a
superset of the FP Server Extensions. Basically, Windows SharePoint Services
runs under Windows 2003 Servers and adds document-sharing and other
team-based features. These features require a database server as well so
they aren't usually included by default just if the host has the FP Server
Extensions installed. Your best bet is to make sure that your host has
SharePoint Services enabled for your account before you begin designing
anything if you want to make use of any of the features of SPS, such as
Document Libraries. Otherwise, if they just have the FP Server Extensions
you can create a normal FP web and use the features normally available to
the FP Server Extensions without issue.
Hope this helps,
Mark Fitzpatrick
Microsoft MVP - FrontPage