From Kate B: "This is a question about self-censorship: about which subject(s) would you not blog/post on Facebook? (I'm not talking about those which you would f-lock.) In other words, when is it *not* 'good to share'?"
I don't post personal stuff to Facebook. I mean, basic life things like going to a concert or traveling to A or B, but not *personal* stuff. As opposed to Livejournal, where I have a range of filters for posting different sorts of things that can be seen by different people. There's very little I wouldn't be willing in principle to post on LJ to an appropriate filter. I think the only things I would not post to LJ is those that would be TMI, in other words that people have no need or desire to read! (Whether I do post something depends a lot on whether I get round to it or am in the mood, etc.)
Anything political though (except internal organizational politics), I always make public. (Also, as someone asked recently, what is posted publicly here may be publicly shared).
I don't know why I don't post personal stuff to Facebook. Well, for one thing I'd have to go and create a whole new set of filters. I know they exist, close friends and stuff, but why bother? If it's stuff I want to tell to a narrow audience, then by and large that audience is also on LJ. Also, I don't know, FB just seems less suited to the long form when people have this whole feed of trivia and photos and linkies passing their eyes. Then again I just got into FB a lot later. And, kinda, probably irrational this one, I just kind of don't trust it as much. It just feels so... open. LJ feels more intimate and secluded. Which is nonsense. Filters and all.
Of course, Facebook is a big mega corporation so the extent it can be trusted with one's privacy is dubious. But then not sure how ultimately trustworthy SUP Media are, that own LJ. It's one third owned by Kommersant which is owned by a Russian oligarch. And, presumably if Vlad the Magnificent were to click his fingers they wouldn't be in a hurry to say "Sorry Mr. P., but our customers' privacy is sacred. We have our principles you know!" On the other hand, although LJ has sometimes screwed up, and many folk lament that it is not the pure, independent, idealistic IT-start up it once was, I think FB have done a lot more nefarious stuff to their users on the privacy front, though I can never keep up with what's real and what's a hoax scare story. But maybe there's something to my reluctance. Like, with FB you never know if they'll be like "Ah, you restricted this post to Close Friends, but then one of your Close Friends commented on the post and tagged one of their Close Friends which means they can see it!" or some such, or sell your deepest, darkest secrets to advertisers who will then try to sell you relevant medications/sex toys/therapy/weapons/cats. That's another thing. I have a permanent account on LJ, so no ads, so I don't run the risk of being confronted with disturbing adverts responding to my deep dark secrets.
So there may be some rationality to my greater willingness to share on LJ than FB, but I think mostly it's just habit and comfort.