WikiSpaces is a commercial wiki authoring product aimed at the education market. It is a very simplified version of the Wikipedia editor, designed so students in K-12 classrooms can use it. It has certain advantages: easier to learn and use than Wikipedia; more secure because only those invited may edit the pages; easier to upload material from one's computer. It has some disadvantages, such as the clunky way of inserting HTML codes. But 99% of the time, you don't have to worry about that stuff.