The differenences between E2 and a Wiki:

• Wikis are content or community centered, E2 is all-pupose and general.
• Wikis usually give unfettered access to the entire document without the by-user grouping that E2 imposes.
• Wikis have a tree structure with a simple starting page and nodes branching off from there, with nodes being uniquely identified by name. E2 has no central page or tree heirarchy.

Contrary to what ponder says:

• Registering is an option in almost all modern wikis, simply due to the idiocy of the average internet user who might stumble upon a wiki.
• Any fully-featured wiki will contain the ability to diff a page and see who made what modifications and what the document looked like revisions ago.