The next question out of a writer's mouth would usually be, "Well now Mr. Smarty McFarty, isn't that what you are doing with your blogs just not as special and important as my books?" and the answer is absolutely not. Don't get me wrong, I have written books, and I am currently working on three more that aren't even close to finished. I just have different goals with my "books" as I post them as blog entries, because I personally can't finish books any other way. That is ME, and not everyone but keep this in mind, if I wake up in the morning and absolutely nothing creative will come out of my brain for the entire day, I can still blog. Can you still write? I have roughly 76 (maybe more) chapters of books I can post whenever my brain is in "freeze" mode. I have a huge graphics library I have been stock piling, and I always have a digital camera to take snap shots of things that are interesting.
Thus is the most important difference between a writer and a blogger. Writing might be the means to an end, but there is an awful lot of "not getting it done" in between your writing projects. Blogging is a state of being, that never really takes you out of relevance, even if it does seem so much less important. Many people keep up a blog to supplement their writing, but believe it or not there are plenty of us out there that keep up our writing just to supplement our blogs.