The purpose of the two resoure are different - The communication resource is for notification or altering - communicating in business logic level, while the auditevent resource is for maintaining a log - recording in software security level.
There will be an audit record every time any record gets created, updated, deleted, accessed or otherwise manipulated. Few people will have the ability to look at audit records.
Communication allows you to surface that information has been shared as part of the clinical record. E.g. “I sent the lab report to Dr. Jones” or “I gave the patient a pamphlet on smoking cessation”.
If you think additional clarity should be added in the spec, feel free to submit a change request.