The Deferred Events tab contains an Add Objects tool that allows you to add already existing events but not to create new events. This list is similar to the list of Business Rules that only reuse elements and does not create them.
The difference between an event and a deferred event is that an event is always instantaneous and dynamically handled by a state, whereas a deferred event is an event that occurs during a particular state in the object life cycle but it is not directly used up by the state.
A deferred event occurs in a specific state, is then handled in a queue, and is triggered by another state of the same classifier later.