[young_unixer]

I don't think those are the important differences.

Reddit has most of that, and a significant amount of subs there are just cesspools of hate.

[unethical_ban]

Points 2 and 4.

HN is like the equivalent of a small, curated, relatively mature subreddit that avoids being discovered by other reddit users.

[anigbrowl]

Accurate, but this is a somewhat imperfect strategy in many contexts. You will probably find this article interesting.

https://snap.stanford.edu/conflict/