RPO refers to the recovery point objective, the time between data recovery points or the backup of the system which will be used to restore the data if a disaster strikes. A lower RPO stipulates frequent backups, and less information will be lost during an unplanned outage.
RTO stands for recovery time objective, the amount of time it takes to recover operations after an outage. The process of bringing back the continuity includes provisioning of resources, and restoration of services from the DR site. A low RTO means more resources pre-configured, faster recovery, and a higher expense.