Recovery point objective (RPO) is used to determine the maximum amount of time between the Last available backup and potential failure point. Recovery point objective (RPO) helps in determining the amount of data that the business can manage to Lose in the event of a failure.
Recovery time objective (RTO) is used to determine the maximum time a data recovery process will take. It is defined by the amount of time the business can afford for the site or service to be unavailable.
Recovery Level objective (RLO) is the objective that defines the granularity with which you must be able to recover data — whether you must be able to recover the whole farm, Web application, site collection, site, list or library, or item.