Plugin versus Module Drupal has many specific terms that can have different meanings depending on usage (e.g. view vs. a Drupal View). It looks like another in Drupal 8 is plugin &amp; module. Generically, both seem to imply extending functionality to existing code (e.g. FireFox plugin, WordPress plugin, Drupal module, Angular module, etc.). However, it seems like they are 2 different things in Drupal 8.

As I understand it, D8 plugins (the incorporation of CTools plugins in D8?) are reusable components like a form widget, while modules are extensions to Drupal 8 core code that can implement or create plugins. Is this correct?
Yes, you're right: Modules are still modules, the equivalent of what WordPress calls plugins. Each module can implement one or more plugins.

For example, the Voting API module has a plugin for each of the methods to show the result: Average, Sum and Count.

Plugins also needs a plugin manager, which is the responsible for actually calling the plugins.

You can see this on:


https://github.com/pedrorocha-net/votingapi/blob/8.x-1.x/src/Plugin/VoteResultFunction/Average.php
https://github.com/pedrorocha-net/votingapi/blob/8.x-1.x/src/VoteResultFunctionManager.php