As well as I can tell, if there is a difference between Gliders and Sailplanes, I would think the Sailplanes have much wider wingspans, but much smaller cords in their wings. A glider could technically be any light airplane that is balanced to not have an engine.
I guess it would be a pretty fine line. Maybe someone at
www.skysailing.com could help us out? I've met Bret Willat and company. Great bunch of people, and they run a fun little operation in Warner Springs, CA.
Oh, hey, I dug it up on my own. Here we go:
http://www.skysailing.com/pages/faq.html#gliderGulfstream Driver was on the right track with his answer.