Alerts are an system you can use to alert your users to updates, outages, or any needed information. The user will see the alert icon in their header display the number of any active alerts on the bell icon. They can then click on that icon to view those alerts.
Alerts are meant to be short, time specific pieces of information. They have a title, detail, start date, optional end date, and optional URL field.
Notifications are templates for email messages that will be sent to the user, while alerts are entirely within the more brief content within the system.