Installing Drupal with the stock installation files downloaded from Drupal.org represents a blank slate for your website. You can install a distribution if your website matches a common use case, like a company intranet or a conference website, and you would like to take advantage of some common features built by other developers.
Distributions (also known as distros) are a packaged group of files including Drupal core along with a group of themes and modules selected to address a particular need.
Different distributions are available to meet specific needs, including meeting the needs of a particular market (for example, governmental or educational institutions), or providing specific, deeply integrated functions into websites such as social media or commerce.
Finding a distribution
Due to the open nature of Drupal, anyone can create a useful distribution others can use to help them start faster.
Other distributions
For a list of available distributions created to address various needs, see Download & Extend on Drupal.org.
Finding more resources
Acquia’s documentation contains articles and resources you can use for reference as you install your Drupal distribution, including the following:
Installing a Drupal distribution for Cloud Platform.
About Drupal multisite installations for Cloud Platform.