Multi-Way Intercom and Group Intercom allows multiple headsets to be connected together for an intercom conversation. The difference between them is how they are set up.
With Multi-Way Intercom, two headsets are paired together in a specific order (A to B, B to C, C to D, etc.). The last two headsets that are paired together will be able to talk to each other over the intercom. The other headsets in the group will need to connect to one of the headsets that are talking over the intercom one-by-one so that they can join the ongoing conversation. This will create a chain where each headset is linked to the headset that they are paired to in the group.
With Group Intercom, one headset is paired to all of the other headsets in the group (A to B, A to C, A to D, etc.). The last two paired headsets need to terminate the intercom conversation between then so that the "leader" (A) can activate Group Intercom and connect all of the headsets together. This will create a chain where each headset is linked to a specific headset in the group depending on the order that they were paired to the "leader".