Check Wikipedia
(Shameless Promotion!!)
http://en.wikipedia.org/wiki/Angel_investor
Essentially, Angels are people who put in their own money into a business in exchange for equity. Whereas a VC fund is a collection of other people's moolah managed by a VC firm. Generally, one of the partners of that VC firm also put in some money of their own as a show of confidence (but thats not a prerequisite).