One of the key differences we believe is the table of contents on the side. Blogs are a modern representation of newspapers, magazines and other periodicals. One of our goals is to see if we can make a modern representation of books.
One nice thing that we have found is that many of our staff actually have multiple sites for different uses. We use one each for our two companies. I've got one between my wife and I. I have one to keep personal notes. It doesn't feel like we are using them just because we built it either.
In many ways I use it like a wiki but organizing a wiki has always been a weak point for me. I always end up with orphan pages with no links to them. Also, wikis are almost categorically ugly for some reason. On the other hand, blogs are often beautiful.
One of our design goals was to be "beautiful." Please check out our template designer. We think it might be one of the best in the industry (blog, website builder, or otherwise).
Sunny