Assign a computer name to each network interface
Names aren’t associated to adapters, it’s the hostname of the computer.

Why it’s the WiFi and not the LAN is basically which one got assigned first.

You only have one entry because, well, you can only have one.  Many routers have a mDNS service (usually attached to DHCP) that manages the resolution of host names to IP addresses.  This is a 1-to-1 relationship.  If you had one name pointing to two different IPs, your computer wouldn’t know where to go.