Some History of Drupal Distributions and Installation Profiles
A Drupal distribution focusses on a certain business and adds features specific to them into one installation so it takes lesser time to configure the most certain elements of a Drupal website. For example, if you’re looking to build Drupal websites for hospital management, your Drupal developers can pre-configure modules for patient registrations, investigations, pharmacy management etc. and also configure roles for admins, doctors, patients, nurses, etc. So now when you want to deploy the same or similar Drupal solution for a different hospital, the work is much lesser and can be done faster.
The first Drupal distribution was built way back in Drupal 4 that was called CivicSpace. A distribution meant for online campaign management and grassroots activism which was originally built for Howard Dean, a United States presidential candidate in 2004. The development team later worked on it, enhanced it and ‘distributed’ the packaged bundle of joy (read code).
After Drupal 6, Drupal.org released tools to build Drupal distribution packages, a number of distributions emerged like Acquia Drupal, OpenAtrium, Drupal Commons, OpenPublish, PressFlow, etc. Drupal 7 saw the introduction of installation profiles that could smoothly assemble a distribution and was less complex than a distribution. Distributions like Commerce Kickstart, eRecruiter, Omega, GrandFoo, etc. were built with Drupal 7. In Drupal 8, installation profiles act like modules wherein they can have access to hooks and plugins, declare page callbacks, declare blocks, etc.