Facebook indeed has similar features. But we should not simply compare features when comparing social platforms. Philippe Beaudoin made a very insightful post about this:
"For a social platform, the implication of turning a feature into a core part of the user experience cannot be overstated. It's because the real feature of social platforms are the way its user base exploits it. If only a few users rely on friends lists as a filtering feature, the feature might as well not be there. But G+ says: "Hey! Welcome! The first thing you should do is setup some filters!" Add a few thousand users and the bandwagon effect will turn G+ into a much different place than Facebook."
"For a social platform, the implication of turning a feature into a core part of the user experience cannot be overstated. It's because the real feature of social platforms are the way its user base exploits it. If only a few users rely on friends lists as a filtering feature, the feature might as well not be there. But G+ says: "Hey! Welcome! The first thing you should do is setup some filters!" Add a few thousand users and the bandwagon effect will turn G+ into a much different place than Facebook."
https://plus.google.com/107988469357342173268/posts/eHccmEr4...