My Mac looks like a PC on my network

I've got two Macs on my local network. One is a Macbook Pro (recent model) and the other an iMac Pro (also recent).

In the past, when I opened my Network folder, I would see the iMac from the MBP and vice versa. But now, on the MBP, the iMac has a PC icon (and the label "PC"). On the iMac, the MBP has a proper Apple icon. I haven't done anything funky network wise, my setup is pretty much out of the box. Any ideas what is going on here?

I've already done most of the diagnostics here: https://superuser.com/questions/881157/why-can-t-i-see-my-macs-on-lan-under-network, but I can indeed see my macs, and can connect/exchange data between them, but they are not appearing as proper Macs.