> One wonders what the difference in behaviors these have is?

"Kill" makes an item be "[dead]", i.e. hidden from users who don't have the "showdead" setting turned on in their profile. A typical case is killing duplicate posts when they don't have an ongoing discussion. "Blast" is like "kill", but also bans the user. A typical case is banning trolls. "Nuke" is like "blast", but also bans the site. That is for spammers.

Oddly enough, no one asked about the most important by far of all these links, perhaps because it also has the blandest name: "edit". That goes to a page where we can edit an item's title or url, or put some moderation flag on a story.

Probably kill = hide from front page, blast = hide from all, and nuke = delete from database (maybe soft-delete). Pure speculation though.

Kill makes it dead, blast makes it trend down the front page fast, nuke is delete/hide. So I believe.

If nuke is "delete/hide," then what is "delete?"

"Delete" is like "dead", except that the posts aren't visible even if you have showdead turned on. We don't ever delete things unless users ask us to—typically because the window for deleting their own post has expired—and then only when they have a good reason for asking. Otherwise HN's bias is toward preserving history.

Coincidentally, I posted something else about "delete" a few hours ago: https://news.ycombinator.com/item?id=7975137.

What does "dead" mean?

dead posts are hidden by default. I believe once you have enough kamra there is a "showdead" option you can enable in your preferences. Dead posts/comments will be marked as [dead], but you can at least still see them.

"dead" on HN is like locking and hiding a thread -- no more voting or commenting and the thread disappears.