New Install.

If you are starting with a clean, new install of Mambo it is recommended that you use the latest Mambo. Currently, this is the Mambo 4.6.x branch.

The Mambo open source CMS is provided in two distributions for each version of the Mambo 4.6.x branch.  These are called "Mambo Lite" and "Mambo Complete".

• Mambo Lite
  This package is the core install of Mambo. It contains all essential core files only. Additional components and modules are available as add-on extensions which puts the power in your hands as to what you install. Mambo Lite does not include Help files or an editor.
  
• Mambo Complete
  This is the extended package for Mambo. It contains an editor, help files, and all the components and modules that have traditionally been packaged as part of Mambo.
  
• Which should I choose?
  If you are just starting out with Mambo, you should download the "complete" package as this will help you to explore the potential of Mambo. Installing the sample data also helps you to quickly learn how Mambo works. (If you are using any version prior to 4.6, you will be downloading the complete package anyway as Mambo Lite packages were not introduced until 4.6). Make sure you use the Help section to help you learn to use Mambo. As you develop your Mambo site you can choose whether to keep the polls, the weblinks, or any of the other extended features provided. Some components and modules are still an essential part of the core functioning of Mambo and they cannot be uninstalled - you will easily see which ones these are.
  
• All core extensions, that is, the add-on extensions written by the core development team, are available for download and are easily installed through the Universal Installer.  Components and modules that were formerly part of the standard Mambo distribution will continue to be developed by Team Mambo.

Upgrading.

If you are upgrading an existing Mambo web site, it is recommended that you check which 3rd party extensions you are currently using, decide whether you wish to retain those extensions, and then check whether your favourite extensions have been upgraded to work with Mambo 4.6 and above.  Many older extensions have not yet been upgraded so this is an important consideration if you have come to rely on the additional features those extensions provide.  The Mambo Team are aware of these issues and are continuing to maintain the 4.5.x branch of Mambo in order to ensure compatibility with older extensions.
The latest version in the 4.5.x branch is Mambo 4.5.5. 
Please Note: The Mambo 4.5.x branch is no longer being developed but security patches will be released when necessary.

If the extensions you use have been upgraded for Mambo 4.6.x, then you should upgrade to the latest Mambo release so you can take advantage of the improved features and functionality.