When a person edits their registration, and I receive an alert, how do I know what they've edited?

I receive an email notification when someone edits their registration, how can I tell what information they've edited? or if they've cancelled their registration? Please advise. Thanks!

The only way to know which fields were edited is to compare the data from the email Notification that you received when the form was submitted for the first time and from the email that you received when the submission was edited.