In TG Online, Events and Alerts are similar, but different. In general they operate in much the same way, and are linked.
Alerts
An Alert Condition is a statement about device information that results in the Alert either being “Active” or not. Alerts will be triggered based on their settings, and can be used to send SMS and Email notifications. You can set up an Event to record times when an Alert is active.
Events
An Event is set up to log and report on all the times an alert condition was active, or simply when an I/O is active/inactive. This is typically used to monitor the run time of a pump or other secondary device connected to a vehicle. Reports will be able to be generated showing the times of use and run times. You can access event reports under ‘Custom Events’ in Reports