Open/Active are the once which are raised but not cleared
As an example , when you set the filter on raised and cleared . You see the below . Note that this event was raised and cleared
When the filter is set for raised , you see the same event which is actually cleared . The raised filter only list the events which are raised and not the active events
Active events are the once which are raised and not cleared , please check the below post where I have included details earlier
CA PM - List only active threshold violation events