From Cloudrexx Development Wiki
|A theme is a collection of files (HTML, CSS, JS, GIF, PNG, JPG), which together determine the look and feel of the website. A theme contains elements such as the header, footer, navigation, sidebar, etc.
Contrexx is shipped with a preinstalled theme. Additional themes can be downloaded from the main website.
|A template is a file that defines an area of the web pages generated by a theme. For example, there is typically a template for the header area at the top of the web pages, a template for the content, a template for the sidebars, and so on. The templates are like building blocks that make up the complete web page.