Facebook is a few-to-few communication network designed for sharing information and life events with friends. Twitter, on the other hand, is a one-to-many information broadcast network. The only way magic happens on Facebook is through reciprocity: I friend you and you friend me back – then information flows. But on Twitter, I can get something out of following Shaquile O’Neil who has no social obligation to follow me back.
Bill Gurley, Benchmark Capital