You've got to be running some sort of trunking program to see that information, a program like Pro96Com or Unitrunker.
On a networked trunked system, peers = neighbors = neighboring sites from the one you are monitoring.
Let's say if you were part of an agency that is on MARCS and you have a MARCS radio, as you travel around you use different tower sites for communications. If are in Columbiana Co, your radio may have determined [based upon RSSI and whatever else] that the best [current] site for you is the Lisbon site, and so your radio will communicate with that site. The Lisbon site's control channel broadcasts [on the control channel] a list of neighboring sites and their respective channel number (LCN) of the neighbor sites' control channels. That is for your benefit, because if you can no longer reliably communicate with the Lisbon tower because of your location, your radio knows to check the control channel of each of the neighboring sites to determine which site your radio should communicate with at that point.
P25 trunked system neighbor sites are "peers". I'm not a trunking expert. I don't know if all types of networked trunked systems refer to neighboring sites as peers or neighbors. I do know that Unitrunker calls neighboring sites "Neighbors" whereas Pro96Com calls neighboring sites "Peers".
So I use the two terms interchangeably, for better or worse, right or wrong.
Mike