Well, Virtual Private Server is available only on our linux VPS boxes (and not on windows). It basically is a server in a server. You get complete root access and a virtual ethernet card. You can configure/install your own programs, software, DNS server, routing tables, etc. You'll also have to configure the web server yourself if you want to host a website. It is basically for those who need the full functionality of a linux server but can't afford to pay for one.