High Availability (HA) is a feature of a deployment architecture which provides resiliency against common component failures and faults, typically through the use of hardware and resource redundancy (for example where "spare" resources are deployed in the primary region in case active resources fail).

A reasonable summary of the relationship between Disaster Recovery and High Availability is as follows:

What is hopefully clear is that both High Availability and Disaster Recovery need to be implemented to provide a satisfactory level of overall resiliency and redundancy.