The biggest additions to Joomla 1.6 compared to that of Joomla 1.5 are Access Control List [ACL], infinitely nest-able categories, One-click extension updates, Semantic XHTML Layouts.
ACL allows site administrators control over who can view and manage the content. Joomla 1.6 provides administrators and creators user-defined category levels that allow them to create category tree. Semantic XHTML Layouts gives a baseline for content presentation and One-click extension updates allows users to keep their site secure and controlled by simplifying the process of updating extensions.
Moreover, Joomla 1.6 has fresh new templates and semantic markup to please search engines which is beneficial for the website. In Joomla 1.6 there is color-coded editor for easier HTML and CSS editing.
There are some SEO improvements too by which meta-keywords and meta-descriptions can be assigned to articles, categories and menu items and articles can change the page header and page title separately. The new Joomla 1.6 API provides an intuitive query building class which allows programmers to build queries thru their programs.
Some more features like new Administrator Navigation menu, “Save and Add” function, new administrator template choices, new module configuration options, improved media manager, and so on.
New features in Joomla 1.6 compared to Joomla 1.5 are beneficial for designers, developers, administrator as well as webmasters.