For some reason, I can't even edit my own post!!!
Anyway,
AJAX doesn't enhance Javascript. It relies on it. Javascript is a client side technology. It is purely run on the browser. AJAX can be thought of as interface between the technologies.
AJAX just uses javascript to communicate with the server in the form of XML. That's all. There's no magical difference between javascript and AJAX, AJAX is an implementation of javascript.
EDIT: the correct link is this:
W3schools