Both the 8811 and 8851 operate in the same way. The 8851 adds a colored display and has USB ports for headsets.
You can learn more about the 8811 here.
You can learn more about the 8851 here.
https://it.brown.edu/services/oit-service-center
For reserved service for a technical consult or a loaner check-out, you can schedule an appointment here.