Unfortunately, the PIEventObject will not give you that information (i.e. which exact Property or Alias was added/renamed/deleted, etc.). As per the PI SDK Programming reference, the EventData property will return a NamedValues object containing the following, in the case of a PIModuleDB type of Event Pipe:
- The unique ID (UID) of the PI Module;
- Its effective date (EffectiveDate);
- Its previous effective date, if applicable (OldEffectiveDate).
The only way for you to determine what really happened on that PI Module, is to "restore" it using the PIEventObject's PassivationString and the PIGlobalRestorer (as you already do), and compare it with what you know was its previous configuration - you probably want to implement your own cache for that purpose (i.e. a collection of the "last known configuration" on the PI Modules you get notified for).
That said, I suggest you contact our regular technical support and file this in as an enhancement request: adding information to the NamedValues collection that's passed to the PIEventObject.EventData, for a PIModuleDB type of Event Pipe.
Hope this helps!