What I find to be interesting about this Facebook vs. Twitter issue has less to do with who people are interacting with on the networks and what information they are sharing, but rather which types of relationship people find to be more valuable and more trustworthy. Now I know this is a bit like comparing apples and oranges since the two networks are used for sharing different information types (for the most part) with different networks of users, but let's forget about these two issues and simply analyze this based on the two different graph designs of the networks.
It is commonly known amongst SNA geeks and many people who study social sciences that the most famous SNA paper published to date is The Strength of Weak Ties written by Mark Granovetter in 1973. Granovetter found that weak ties, basically more distant friends in his study, were positioned to be sources of new information more so than close friends. This idea comes down to the fact that you generally know about the same things as the people you spend a lot of time interacting with, and that new information typically disseminates through your weak ties (technically bridges), people who interact mainly with people outside of your network, who would be sharing different information.
Now considering the two social networking site's (SNS) graph designs from a high level without getting into the different ways different people use the sites, let's agree for arguments sake that one typically uses Twitter to connect with weak ties and one uses Facebook to connect more with strong ties (even though we all have "friends" on Facebook that we aren't really friends with, but I will save the argument that a perfect SNS would have an infinite amount of relationship types for another day). So Twitter = weak ties, Facebook = strong ties. Immediately, the discovery of new and valuable information is more likely on Twitter, making it more valuable right? Well not so fast Ghostrider, some not so recent data (2008) for the real-time world that we live in found that far and away the most trusted source of information was "an email from someone you know", with 77% of people validating this referral type. On the other hand, only 43% of people actually trust the social network profiles of people they know, making me wonder how much they would say they trust the information they receive from people they don't technically know on a social networking sites (SNS) - i.e. a weak tie.
When Granovetter explored the topic in 1973, he considered only symmetric relationships as to not complicate his formal math experiments for his thesis (if you want to get into that go read the paper). Considering the expanded opportunity of developing new relationships on the Internet, it doesn't really make sense to define a weak tie on a SNS the way Granovetter defined them in '73 based on 1) amount of time 2) emotional intensity 3) intimacy (which he defined as mutual confiding) and 4) the reciprocal services which characterize the tie. Anyone who uses Twitter follows people with whom they are not intimate (based on Granovetter's mutually confiding restriction) and by nature and purpose the services aren't reciprocal, but the amount of time and emotional intensity for the follower could still be high, so how weak or strong really are the ties on these networks - sigh, the grey area expands.
This can all be boiled down to this: do you typically value a referral of some sort of information more from a symmetric "strong tie" on Facebook or from an asymmetric "weak tie" on Twitter? (Hold the information type constant in each situation). And secondly, do you trust a referral more from one tie more than the other? And without getting into semantics, yes the two are different (I did just kind of get into semantics huh?). Obviously there is no right answer considering it is somewhat of a subjective measure and a more complete argument would have to take into consideration different information types being shared, but I invite you all to share your own sentiments on the matter.
It is without a doubt in my mind that as we move forward and SNS's evolve we will begin to make sense of some pretty amazing structural, "macro-level" patterns that happen in our society because of the data we will be able to extract from the microscopic relationships within social networks. I have said it before and I will say it again, we are only at the tip of the iceberg on this stuff.
