I found an implementation of an event loop and would like to compare it with an overlapped IO. Both code can work on Windows but we will leave the nuances of using it on any one platform. The semantics of an Event Loop is that some events are added and at the end of a timeout these  events are triggered. The timeout is determined if the events needs to be triggered the next time and if so the timeslice to wait, otherwise zero. Several helper threads can wait on  a set of poll able resources. The threads are kicked off by the loop, then waited on and then shut down.  The wait is for the timeout determined.  If this is successful, we will then recalibrate the before, timeout and after for the next round.
If the wait set was not successful, then it was probably because events got added or removed, so we check all the states and start all over.
There are a set of three lists maintained : a doubly linked list that is not full , a doubly linked list that is full, and a doubly linked list that is empty. The waiter thread moves between these queues.
In an overlapped IO this is very different. Where the events are serviced by different producers and consumers and can even associate it with multiple poll able resources.
There is no prediction to which order the events will get triggered in either case but one proceed in terms of beats and another proceeds in terms of the items in the IO.