What's so special about this Mac memory management? It uses the SSD better and makes swapping faster? It predicts what I'm gonna use or stop using and it swaps in/out accordingly?

I'm not sure. I think it does swap more aggressively. I think the disk is also just really fast and has a higher speed connection to memory.

Qualitatively I'm running way more things in the background than I could on Linux and Windows machines with double the RAM, with far fewer hiccups.

I haven't tried a modern Surface or other high-end Windows laptop so maybe their swapping is comparable, but given the shocked reactions of non-Mac users at 8 GB of memory, I don't think so.

All of that is a yes, plus compressed memory is a big component of macOS.