A lot of the macOS networking stack (at a lower level) comes from FreeBSD. People have argued that the BSD network stack is superior to Linux whereas Linux runs applications faster. At a low level, I think this is still accurate.
I’m a Ruby developer but I tried to port a Linux application written in C to macOS before and it was mostly rearranging positional arguments to system API calls; however there’s probably a lot more going on that I’m not aware of too.
“Ice” lol. It’s an acronym, ICE.