When should we use Component event and application events?

It is best to always use a component event instead of an application event. Component events can only be handled by components above them in the containment hierarchy, therefore, their usage is localized to the components that need to know about them.

Application events are best used for something that should be handled at the application level, such as navigating to a specific record. Application events allow communication between components that are in separate parts of the application and have no direct containment relationship.