Similar

• Both are full-featured free and open source web applications with which you can realize a very diverse variety of projects.
• Both are written in PHP and use a database such as MySQL
• Both can run on standard, inexpensive hosting.

Different

• Drupal is more of a Content Management Framework, whilst Tiki is more of an out-of-the box Content Management System with all the features built-in. Because of these design choices, Tiki has more features out-of-the-box. With Drupal, you can add tons of features via modules.
• Tiki is more centralized. Tiki is the all-in-one model while Drupal (like Joomla!) is the small-core-and-add-what-you-need model. Each model has its pros & cons.
• While Tiki is a very large and popular project (over 200 contributors to main code base), Drupal is several times larger.
• Tiki is Wiki-centric, whilst Drupal is node-centric. Please see (if) Why Wiki Syntax Is Important to your project.
• The Wiki engine in Tiki is mature, very powerful and versatile and has features hardly any wikis have such as Wiki Page Staging and Approval and the cross lingual wiki engine, whereas, the Wiki modules for Drupal are more modest and less actively developed.
• Drupal has modules for features that Tiki doesn't have, ecommerce for example Tiki5 now has a basic shopping cart.
• Drupal 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.

Ohloh

CMS Match

http://www.cmsmatch.com/compare/content-management-systems/11+1073

CMS Matrix

Compare them at http://cmsmatrix.org

Example:

See full comparison by checking them both on http://cmsmatrix.org

Active contributors

Number of contributors who made changes to the project source code each month.

Alias

• Drupal