Hi @Suggy,
Trying to keep it simple:
Notifications [sys_notification] - are where you create, manage and send emails. Think of this table as basically the email itself if you like, however you also configure everything associated with the email.
Notifications allow you to specify what is sent, who it is sent to, and under which conditions to send it (which is all configurable).
Within this area you can also define a specific event if required. (Here's where the overlap and dependence is set if required.)
Events [sysevent_email_action] - are typically script-able logic and allow you to check when certain conditions occur and to take some kind of action in response to the conditions.
A notification (email) could be dependent on an event. For example, a comment has been inserted (You'll see events such as incident.commented already available for you against the incident table).
You have the ability to create you own events if required.
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Thanks, Robbie
