Why Facebook will never be Twitter

On Thursday, the world’s most popular social networking site rolled out some new features, the kind that inevitably lead bloggers to indulge in a new kind of parlor game: comparing Facebook to Twitter.

As Twitter users have been doing for years, Facebookers will soon be able to “tag” other users within their status updates by inserting an @ symbol before a friend’s name. Facebook has also started testing a “lite” version of its site that removes some of the clutter and makes it all look a little simpler — a little more like Twitter.

Don’t get me wrong, I think these features will enhance Facebook and allow more people to use it in more ways. And its slow metamorphosis into a Twitter hybrid, which began in earnest when the site reoriented its design around the news feed in March, is both a validation of the success of the smaller microblogging service and a sign that competition in the social networking space can breed useful innovation.

But these sites are not on a collision course, as BusinessWeek columnist Sarah Lacy suggested in March and as popular belief would have it. Facebook can never complete its District 9-like metamorphosis, and Twitter will always have a value all its own.

The reason is simple: privacy.

As much as Facebook would like to become part of the public real-time Web -- a juicy prospect for marketers -- the vast majority of its 250 million users have no interest in sharing their thoughts with the world. From my reporting and my own experience using the site, people are growing more concerned about who can see their photos and status updates as the overall population grows, and as aunts, uncles, bosses, exes and the like edge into view.

Facebook is the private party. Twitter is the public square. This line has been drawn and there's no reasonable change either site can make to step across it.

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