How is Facebook different from Twitter?
Facebook appeals to people looking to connect or reconnect with old friends and family members or find new friends online. It provides features like e-mail, instant messaging and image and video sharing. Twitter, on the other hand, allows you to post ideas in small size chunks and use these updates as points for others to comment on or react to.
The usefulness of Twitter is not as obvious to some people as Facebook. It is considered to be a lot more addictive once you get the hang of "tweeting" as you get more immediate responses and it seems to live somewhere between the worlds of e-mail, instant messaging and blogging. Twitter encourages constant "linking out" to anywhere.
Where you can only have 'x' number of friends on Facebook, you can have millions of followers on Twitter and this makes it a place to share your thoughts, evoke reactions and create a difference.