Having a high-visibility post on Reddit meant a stressful few hours and some of the most toxic interactions I've experienced.
Maybe it's just a dev thing. Some programming languages can have some really toxic fandom :D
The important part is that HN isn't an echochamber, you get many viewpoints here.
The quality and type of comments were identical on both platforms.
HN specifically seemed to be commenting based on the title and other comments alone. The most common thread of discussion was clearly explained in the first paragraph.
I mean collectively to this website, not to you in particular
A link from HN: Usually comes with thoughtful discussion, and a detectable but temporary uptick in site donations (it's an ad-free, reader-supported project). There are always some detractors, but that's to be expected.
A link from a popular subreddit: A LOT of site traffic and server overload (once in 2015, Google Analytics showed over 6,600 concurrent visitors from /r/TodayILearned), and a lot more bile in the inbox and discussion thread. No uptick in donations.
No surprises there really, but it's useful to verify assumptions.
HN mods are pretty lenient overall and really seem to only ban after numerous rule violations after giving numerous warnings.
People come to HN comments to have a constructive debate, so they are less likely to downvote for disagreement. I often upvote comments I disagree with if the point is well made.
People come to Reddit to have their beliefs confirmed. The subreddit structure reduces mixing between users with different beliefs, and where that mixing does occur, e.g. on the large subreddits, it tends to turn into a downvote battle.
^ It's not really about intelligence but openness to new ideas. You can have one without the other.
But both flag and downvote are karma-gated (I think the threshold is 500 for both, but I could be wrong.)