What is the difference between release procedure with classification and without classification and when are they used?

The release procedure with classification deals with the purchase requisition it can be released both at item level and at the header level. Coming to release procedure without classification can also be used for purchase requisition which is used for item level release only. All other external documents cannot be released with classification. These two procedures are mutually exclusive to say, it has to be decided in favor of one of them only.