High Availability Configuration (HA) is a primary/secondary failover configuration that provides redundancy.
Clustering provides redundancy
and scalability by distributing read and write load across multiple nodes or servers.
A cluster is a group of servers or nodes performing basically the same function but, because they work together, the services they offer are better protected from failure (if this is the desired purpose of the cluster, redundancy) or they can serve more clients at the same time (by splitting the service requests between them, feature called load balancing).In some cases, the 2 features (redundancy and load balancing) can be used at the same time.
