The old wiki is indeed erfurt wiki. Old, simple, limited, reliable.
OU wiki is the Open University wiki - it has limited functionality and navigation but is very reliable. You also need to install OU search along with it to make it effective. It supplements and doesn't replace eWiki
or nWiki (see below).
When you install nWiki you replace
eWiki and get either a fantastic full-featured wiki with all the features you'd expect from a wiki, great navigation and integrated discussions and some neat extras like PDF export
You'll get a mass of problems, admin headaches and a wiki that students can't save changes to if they use IE
. And if that happens you won't know which till you've done it, won't be able to go back to eWiki nor will you be able to fix it easily if it is wrong. (You may be able to guess my experience
nWiki is set to be the 'standard' wiki as from moodle 2 - however at the moment the problems, options and legacy systems of wiki provision in Moodle is, in my opinion, it's single greatest weakness for teaching/learning/collaboration - we've run out of time to get nWiki wokring in IE so we're using OU wiki but hoping nWiki will work sometime soon.
Hopefully this will help clear up what's what and alert you to some of the potential associated issues.