Understand the difference between a Bitnami stack and a Bitnami module
Bitnami installations come in two formats: stand-alone stacks and modules.
If you only want to install one Bitnami-packaged application, then just download and install the stack. It will contain everything you need to run the application.
If you want to run more than one application, you may want to download a LAMP, MAMP or WAMP stack, which will enable you to install several application modules on top of it. That way, all of the Bitnami-packaged applications you want to run will share a single instance of Apache, MySQL and PHP, which will save space and improve performance.
To download a Bitnami stack or module, visit the Bitnami download page, select the application you want to install and then click on the download link for your operating system icon (Windows, Linux, or Mac OS X).