But I don't think it's a meaningful distinction to begin with. Usenet was an endless time sink to get angry at things that didn't matter and argue with strangers who might not even be real people. It wasn't monetized, but it still made it easy to waste years of your life.
HN has an algorithm that manipulates what you see, and we do not know at all how it works.
- The focus isn't on connecting. It has a "friends" feature (I believe?), but the social graph is extremely weak.
- You are not expected to use your real name. On the contrary, it comes off as weird unless you're a celebrity.
- There is no algorithm maximizing engagement, or at least not a hyper personalized algorithm that analyzes your scrolling speed and every sensor under the sun feeding into a machine learning system designed by professional psychologists to keep you hooked.
- Individuality isn't as encouraged. The user name is small, and there are no avatars, or at least used to be (I don't use the new interface very much). The focus is on the content instead.
I suppose you can find a definition of "social media" that includes Reddit, and surely the differences are fluid, especially since we can recognize some efforts by Reddit to become more like the real social media sites, but I vote for putting it in a different category for the sake of discussion.