Hi Cathi,
A fine question by all accounts. Really, the difference is that a blog is your own personal thread, like an online diary, or a story. It's your own space, to do with as you wish. People can comment on it, but that can't add to it, and it is entirely up to you which direction it takes.
Some people use blogs to give an insight into the lives they lead, others chose to tell the story of a fictional character, some mix the two together, or do something completely different.
it's your own little section of the web to express yourself as you please.
For me, I shall be using it as a diary/news page of WO.
Does that make sense?
