An ESXi host is a node in a Cluster. At a minimum, each Cluster has 3 ESXi hosts that are used to implement a functioning VMware environment.

In terms of implementation, an ESXi host is a Compute instance that is configured with the chosen bundle of VMware software.

Notice that an EsxiHost object has its own OCID (id), and a separate attribute for the OCID of the Compute instance (computeInstanceId).