A general description for each button is below: (and/or review blog article to see example).
The 'Reverse' button will create a new timesheet that is exactly the opposite of the timesheet(s) selected. If the original entries were positive, then the new entries will be negative. So the net outcome is that the original timesheet and reversed timesheet offset each other, for a net result of 0.
Note: The 'Reverse' option will have the same effect as voiding.
The 'Correct' button is used to make an adjustments to Costs and/or billing rates on timesheets. The method will create two new timesheets for each selected timesheet(s). One timesheet is exactly opposite of the timesheet(s) selected to reverse it out, and the second timesheet has the new rates that you chose to update based on Project Number and Cost Category. You can update or override these fields: Unit Cost, Overhead-Unit, Overhead-Percent, Billing Type, Billing Rate, and/or Markup Percent. If you save the reversed and corrected timesheets to a batch, you can review before you post.