"Revise and Resubmit" vs "Approved - conform as noted" - when do you have to use the first over the 2nd.

Due to turn-around times by the time the contractor gets it back - they can just submit the following month that is that much fresher, I prefer when OR's or who ever is reviewing a schedule simply do Approved - as noted, because they can tell you to make the same changes with either designation.  But when reviewing schedules - I do not know if there are legal issues of doing the AAN vs the R&R - thoughts?