Twitter is like those newspaper headlines that you see on lampposts. Just a quick bit of news to encourage you to investigate more. Minute-by-minute information of what is happening right now.
Facebook is like a newspaper that you buy and scan through, picking out the interesting bits and throwing the rest away. Day-by-day information of what is happening in your world.
A Blog is like a magazine, that you read more thoroughly, and perhaps even keep for future reference.
A Website is like a coffee table book with lots of detailed information on a subject you are really interested in.
And all of this is so we can stand around our Virtual Braai and discuss topics that are close to our hearts.