Custom actions and custom events are two different timeline data types the usages for which are different as well.

Custom actions are used to denote any actions per screen performed on nonnative controls e.g. tap on an image that is considered a button.
Custom events are used to denote any information not tied to a screen that you would like Appsee to track and to be present in the timeline e.g. errors, form data (search, registration), etc.