>>16
The syntax it adds is simpler, for example it adds "sentence" as a replacement for cons. sentence is simpler because it doesnt allow nested lists. Logo was orginally designed to teach children to program.
In fact I would recommend Logo as a first Lisp for teens to learn, and the author who wrote Simply Scheme also wrote books for teaching Logo which he gives away for free here:
http://www.eecs.berkeley.edu/~bh/logo.html