The original, first-ever wiki was created by Ward Cunningham, a professional software developer, and is still located at http://c2.com/cgi/wiki. It was originally called the WikiWikiWeb. When other wikis, inspired by the WikiWikiWeb, started popping up, the original wiki acquired several other names, to distinguish it from other wikis: The C2 wiki, Ward's Wiki, etc. For the purposes of this wiki, we will just call it the original wiki.
The overall topic of the original wiki was/is an 'informal history of programming ideas'. It was written by a computer programmer, for computer programmers, and was populated mostly by computer programmers, talking about computer programming (and anything even vaguely, remotely connected to that). As such, the original wiki is significantly different from today's most famous and popular wiki, Wikipedia.
Whereas Wikipedia is intended to be an encyclopedia of just about everything, presented from a neutral point of view, the original wiki was more of a community resource project, and so represented many different points of view simultaneously. Since the original wiki dealt with computer programming ideas, and was open to innovation and brainstorming, it could be categorized as a concept wiki, whereas Wikipedia would more properly be categorized as a document wiki. See also This wiki is not Wikipedia.
This wiki, the Atheism United wiki, as part of the overall Atheism United project, is intended to unite atheists of many diverse points of view, and so would best be served by starting out more along the lines of the original wiki, as a concept wiki, focused on the overall topic of uniting atheist activists.