NAS Units have memory, embedded firmware, and thus can be fitted by the manufacturer with embedded programs.
Most Entry Level NAS unit has ftp server. I.e. you can put the NAS by it self on the Internet connection and it will serve files through the Internet.
Both units that you mentioned has ftp server to put an actual Web Site you need an HTTP server.
The Synology DS101G+. unit also claims: ?Web hosting support. A simple static web server for SOHO and home users. Easily build a complete self-owned website for business or family members?.
I do not know what Web Station specifically entails since their description is in a none technical language. I would suggest contacting them and finding more about this feature.
About NAS?
http://www.ezlan.net/nas.html
:sun: