What is the difference between an Ansible module and an Ansible plugin?

Modules are the units of work that tasks run, usually on the managed host. Plugins extend Ansible itself on the control node, for example how it connects, where it gets its inventory, or how it shows output.

• Modules do the actual configuration work: package, copy, service, user. Each task calls one.
• Plugins are code you add to Ansible to extend it and adapt it to new uses and platforms. They run inside Ansible on the control node. Examples by type:
  • connection plugins: SSH, WinRM, network_cli;
  • inventory plugins: read hosts from AWS, VMware, a CMDB;
  • callback plugins: change how results are displayed or logged;
  • filter plugins: transform data in templates.

Rule of thumb: if it changes the target system, it's a module; if it changes how Ansible behaves, it's a plugin.

Go deeper:

• Introduction to modules (official docs) — modules as self-contained units that usually run on managed nodes and return results.
• Working with plugins (official docs) — the full list of plugin types (connection, inventory, callback, filter, lookup, strategy and more).