1972 Unix V2 "Beta" Resurrected

Spock levels of fascinating from me. I want to learn how to compile a pdp11 emulator on my mac.

What’s the difference between an emulator and a simulator in this context?

There is LOADS of gray area, overlap, and room for one's own philosophical interpretation... But typically simulators attempt to reproduce the details of how a particular machine worked for academic or engineering purposes, while emulators are concerned mainly with only getting the desired output. (Everything else being an implementation detail.)

E.g. since the MAME project considers itself living documentation of arcade hardware, it would be more properly classified as a simulator. While the goal of most other video game emulators is just to play the games.

Not the case at all. Tons of emulators are near 100% accurate.