Yes, there is a big difference between a discussion forum and a blog. Blogs are great for putting your feelings out there, with full control over whether and how folks respond. Discussion forums are great for throwing your hat in the ring and then letting things flow from there, taking whatever directions all the various members of the discussion forum wish to take it.
FaceBook is a great alternative to a blog. I've used FaceBook Notes instead of a blog for almost a year now. It allows you to get replies, from selected people.