While DRS is a feature that allows the automatic placement of new and running VMs to hosts, which can ensure resource requirements are met, VMware vSphere High Availability (or HA as it's commonly referred to) is a feature that helps restore VMs to a running state in the event of an unplanned host failure.
It's important to understand that HA is for unplanned outages, such as a component failure in a host. VMs running on a host that suffers an unplanned outage are shutdown when the host fails and are powered up on an available host within the cluster.
While HA is enabled at the cluster level like DRS, it functions exclusively at the host level, so a failure in vCenter will not prevent HA from working normally. In fact, HA is a ...