TL;DR

Automations share a lot of concepts with Events and Actions.

You could think of automations as a special purpose, optimized version of Events & Actions.

• Automations are designed to run a plan of WOs, like a maintenance schedule (PM), or to do Predictive Maintenance (PdM) where something looks like it is about to go wrong,
• Automations can also instead of or in addition to creating WOs they can call out to control devices or make any API call you want

Details

The Work Orders that Automations create are often called 'PMs' or 'Preventative Maintenance Work Orders' (PM WOs), but as above, the automations don't have to create WOs, they can call out to APIs to control devices such as IoT devices, so Automations can have actions that turn a device on or off, or tell a robot to drive itself to the repair depot and then also have a work order for the work.

See also the discussion in Events and Action Intro