Data replication is the copying of data from a primary cluster to a backup or secondary cluster. Through data replication, the secondary cluster has an up-to-date copy of the data on the primary cluster. The secondary cluster can be located far away from the primary cluster.
Failover is the automatic relocation of a resource group or device group from a primary cluster to a secondary cluster. If the primary cluster fails, the application and the data are immediately available on the secondary cluster.