Decision Maker is the individual requesting time off. If the time off is less than 5 days, they enter it into PurelyHR and the Approver approves it. If it is 5 days or more they will seek advice from everyone impacted by the vacation. With all the advice and perspectives the decision maker has received, they choose what they believe to be the best course of action.
Vacation Approver is the person that is required to approve the decision in PurelyHR. It is not up to their discretion to approve or deny a request, it is up to the Decision Maker. It is their responsibility for any impact created by their vacation.