Alfresco Process ServicesAdministrator can show the process data and manage the configuration of multiple clusters. In this context a cluster is a number of Process Engines that logically belong together. Note that this does not relate to the way that these engines are architecturally set up: embedded, exposed through REST, with or without a load balancer in front, and so on.
Also note that the Administrator is capable of inspecting the information of each Process Engine (if configured correctly). It is not, therefore, solely bound to using the Process Engine in Alfresco Process Services, but to all enterprise Process Engines.