Drupal uses three main types of packages for its system.
Drupal modules – Modules are collections of functions that extend Drupal. They enhance its functionality. For example, maybe you need to integrate with an email management tool that’s not included in Drupal’s core features. You can add that functionality by using a module the community has contributed or by creating your own.
Drupal themes – they set the look and feel of a Drupal site. It’s a file or collection of files (PHP, INFO, CSS, JPG, GIF, PNG), and contains elements such as the header, icons, block layout, etc. You can download and install themes the Drupal community has already contributed, or build your own.
Drupal distributions – A Drupal distribution is a downloadable package that includes Drupal core and a set of contributed modules, themes, and configurations. It’s like a starter-kit that combines features and functions tailored for a specific kind of site. Building a distribution is usually a task for advanced Drupal contributors, but you can download and install distributions the community’s already contributed.