- Both Tiki, TWiki (along with XWiki_old) are free and open source enterprise/applications wikis.
- Both support Wiki markup. Please see (if) Why Wiki Syntax Is Important to your project.
- The names of the projects are similar and sometimes confused
- TWiki is written in Perl whereas Tiki is written in PHP.
- Tiki hosting requirements are easier (shared hosting)
- TWiki uses files for storage whereas Tiki uses a database, such as MySQL.
- TWiki is GPL, Tiki is LGPL. The main difference between the GPL and the LGPL is that the latter can be linked to (in the case of a library, 'used by') a non-(L)GPLed program, which may be free software or proprietary software.
Compare them at http://www.wikimatrix.org/compare/Tiki-Wiki-CMS-Groupware+TWiki
"..All in all. I was up with TikiWiki in no time…
To my surprise, it looked more refined than Twiki, the UI was more intuitive, not cluttered. Finding and setting up information was easy..."
There is a fork of Twiki called FosWiki.