Re: Control of Documents
At my organization (ISO 9001:2008 semiconductor manufacturer), we describe the changes generally on the ECN (change notice). For example, if all changes relate to the use of a new tool, we just say "Revised to reflect use of new tool." If the changes aren't too plentiful, we also route the document for approvals with "Tracked Changes" turned on in Word to show exactly what changed. The description in the revision history, however, is a general summary. Auditors have never had a problem with that.
Down the road, if an engineer wants to see exactly what changed between two revisions, they do a "Compare and Merge" in Word to show the changes.