Similar

• Both TikiWiki, TWiki (along with XWiki) 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 😊

Different

• TWiki is written in Perl whereas TikiWiki is written in PHP.
• TikiWiki hosting requirements are easier (shared hosting)
• TWiki uses files for storage whereas TikiWiki uses a database, such as MySQL.
• TWiki is GPL, TikiWiki 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.

Wiki Matrix

Compare them at http://www.wikimatrix.org/compare/TikiWiki-CMS-Groupware+TWiki

Review

"..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..."
-- http://xmltech.wordpress.com/2008/11/11/stint-with-a-cms-twiki-installations-and-problems/

There is a fork of Twiki called FosWiki.

Alias

• Twiki