We are working on an effort to provide some guidance on monitoring the health of a Group Chat deployment and included are these two counters:
When you are monitoring even a small setup the numbers would be assumed to be equal but in fact the Active Endpoints will likely be higher at some point as that counter is for the number of applications launched against the system, the two applications are the Group Chat Client (GCC) and the Group Chat Administration Tool. If you logged in to the Group Chat Client on multiple workstations the Active Endpoints counter would increment for each instance but the Active Users would not. If the administrators of the system are running both the Group Chat Administration Tool and the Group Chat Client this too would increment the Active Endpoints counter but not the Active Users counter.
I trust this helps more than the Performance Counter explain text of : The number of Active Endpoints! Feel free to contact me with any other questions, clarifications around Group Chat as this is my current focus.
maybe for a while I’ll sign with TomL GCKid
PS Thanks to Ariel for providing counters from their deployment and asking for clarification.