I did some core research. Let's define what we are talking about for Fortigate firewalls:
1. Name. This is the official conical name as it appears in the config. Under normal conditions it can't be changed.
2. Alias. This is the SET ALIAS command under the config of the interface. It shows up in parenthesis in the GUI next to the conical name.
3. Description. This is the SET DESCRIPTION command under the config of the interface. It is labeled "Comments" in the GUI.
There does seem to be a change in how these three things post to SNMP on newer firmware. I have to leave for the day but will post more info tomorrow.