Recently a relative asked me to explain the difference between homeschooling and unschooling. After I explained it, she still wasn't totally satisfied, but maybe wasn't sure why, so I told her I'd look around for some articles.
Here's a good one I found at the site of the Family Unschoolers Network. It explains the history of the terminology as well as the differences. With a slight bias towards unschooling, I suppose, but hey, I'm totally biased, too.