I would say yes, that's a good way to make the distinction. It's even more than that: the feed is different for every single user.

With a site like HN, everyone sees the same front page at a given time. What makes it to the front page is primarily determined by all users voting up articles or moderating them. Yes, there's some algorithmic sauce behind it that weights votes and flags differently based on some other criteria, but the dominating factor is user votes and flags. And, again, everyone sees the same ordering of articles if they load the page at the same time.

HN is centered around topics and articles. Social media is centered around individuals and what they personally choose to post and promote.