Portal vs Site

A portal is generally a vehicle by which to gain access to a multitude of 'services'. A web site is a destination in itself.
As such the term website refers to a location on the Internet (see this) that is unique and can be accessed through a URL (see this). By that definition a web portal is in fact also a website.
However there is a distinction between the two terms based on the subject and content of the website.
A website is also a web portal if;
It transmits information from several independent sources that can be, but not necessarily are, connected in subject; thus offering a public service function for the visitor which is not restricted to presenting the view(s) of one author.