While backup is designed to provide data protection and archiving, replication is designed to reduce Recovery Time and Point Objectives (RTOs and RPOs) by providing very fast recovery. It ensures business-critical applications and systems are always available even after an outage.
Recovery objectives are a measure of your disaster recovery plan. Making a decision on whether to backup data or to replicate business-critical systems, how often to backup, how much downtime you can endure and how much data you can stand to lose is determined by setting your recovery objectives
In my opinion, all data flowing through an organization is critical. Organizations must therefore first consider how much downtime they can endure before it begins to impact the business negatively. Also known as the Recovery Time Objective (RTO).