HN allows anything that "hackers" might find interesting. On lobste.rs, anything that's not directly programming-related is generally off-topic.
HN encourages self-promotion, lobste.rs discourages it.
Until recently lobste.rs was very actively anti-AI. Newer rules have rolled that back somewhat, but there is still a rather vocal anti-AI contingent that is not afraid to pick fights with people who openly admit to being interested in machine learning as a technology.
HN does the same thing with blockchain. Someone earlier wrote "People only ever work for cryptocurrency companies in the first place because they're scammers themselves" - which would include nearly everyone anyone in the finance or payments industries.
Ignoring the actual submissions, which are usually mirrored on HN, I find the small user base often doesn't offer much in interesting comments. Many are short with little value, and I don't recall seeing many submission authors piping in, or luminaries with the deep knowledge that you sometimes see drop in on HN.
Friends tell me there is a definite political bias that leaks out.
I think Hackaday is a good alternative for hardware oriented HNers.
Go and compare it with HN on any big recent story and judge for yourself.
1. They have abandoned their former policy of “everything non-programming related is off topic” to allow discussion about politics
2. They have lost most of their users. It’s like a ghost town.
HN have some flaws but is still the gathering place for many technical people.