[p1esk]

A social network site is a site where you go to interact with other people.

[dwaltrip]

Your definition glosses over important distinctions between different kinds of "sites where people interact".

[p1esk]

Any definition will suffer from it because on any single site different people interact differently.

[dwaltrip]

Yet there are still meaningful distinctions that can be made.

For examples, it is easy to identify very key differences between Facebook and HN.

[p1esk]

I mostly use Facebook to look at the recent submissions in the Deep Learning group. I mostly come to HN for SV gossip, and to stroke my ego.

Perhaps instead of trying to see the differences, you should look for similarities. For example, how addictive is the site?

[dwaltrip]

The OP commented how sites like Facebook and Instagram seem to distort people's view of what is a normal or good life, as often only the best moments are shared on the site. And this affect can happen even if you are aware of it.

HN is mostly about discussing specific sorts of topics, and doesn't have much of a personal profile, so it is likely that affect is far smaller here.

As for addictiveness, I would agree with you that they are similar along that dimension.

[p1esk]

You don't think reading about 300k SE salaries, or startups valued in billions before they turn any profit can distort people's view of what is normal, or good life?