Now, Facebook is effectively a feed too. So are they just different channels? Although many Twitter clients can be configured to automatically post Tweets to Facebook too, allowing users to maintain two separate social networks (like work and play), I don't know many who actually use it that way.
Digging deeper, a recent study of the two social networks found that 87% of Americans knew about Twitter, and 88% knew of Facebook. Yet only 7% of Americans actively use Twitter, whilst 41% actively use Facebook. Worldwide, Facebook currently has over 500 million members, whilst Twitter has around 100 million members.
So why is Facebook so much more popular than Twitter?
Here the nature of the connections within each social network may hold the answer.
There's an idea within sociology called Social Capital, which seeks to measure the value of the connections in an individual's social network. The idea being the greater the quality of your social connections, the greater your productivity and opportunities. "It's not what you know, it's who you know."
Social network researchers refine this idea into two subconcepts: bonding social capital and bridging social capital.
Bonding (also called Closure) is the tendency of like-minded individuals to form connections amongst themselves. The community that emerges from these interactions is densely interlinked, and social proof and reputation become powerful forces.
Bridging (also called Brokerage) is the function performed by people whose relationships bridge across structural gaps in social networks. Brokers introduce people from previously unconnected social networks, and help information flow between disparate communities.
These concepts can be seen in this diagram, taken from Wikipedia. A densely linked community on the left, with a couple of brokers bridging the gap to a smaller community on the right.
Facebook is a bonding network, dominated by strong ties between friends and families. Whereas by encouraging weak ties, Twitter is designed to be a bridging network. Users can follow distant strangers, and high quality information can quickly spread between closed communities by the retweets of brokers.
Most social networks tend to contain many more bonds than bridges. So the reason why Facebook is much more popular than Twitter might be because, collectively, our urge to bond with friends is stronger than our desire to bridge with relative strangers.
On reflection then, it's probably best not to tweet about what you've had for breakfast; but it might make a friend on Facebook smile.