Anyone else not even use social networks anymore? Privacy or not, it's just garbage. Facebook, myspace, hello, whatever it's all the same crap with different CSS values.
Forums are typically considered social networks, although I suppose the definition is debatable. Whether users discuss their daily lives is not the standard, though. On Twitter everyone just kvetches about the news, and it's still a social network.
I haven't started hearing the term "social network" until myspace showed up. While forums may be that by some technical definition, in practice, there seems to be a core difference.
For one, forum communities tend to be focused on a relatively small group of people in that forum.
Twitter, Facebook, etc., tend to be fully global with the idea that anyone can access anyone else. Presence of media, I think, also matters a lot. On many forums media exists, but is not visible to unregistered users. There's an aspect of "you join or you're an outsider, and if we don't like you we can make you stop joining".
I don't know if I can straight up define it but there seems to be some fundamental difference between Facebook and your random hardware forum.
Do we even need social networks anymore?