Revision History shows you the changes made to the document in OneDrive as separate revisions that provide details such as the time, date, and author name (for external users, the email ID is displayed). It enables you to view the exact changes that were made to the content during each revision. You can also select the check boxes for any two revisions and select Compare to compare them. Details of edits made by users that other co-editors invite for co-authoring are also displayed.
NOTE:
The Revision History functionality queries the OneDrive repository and is only applicable while a file is in co-authoring mode. After check-in, the command is not available.