You know blogs have comments these days? So there is some back and forth.Absent a business use... Blogging is a one-way conversation. A soliloquy. Why on earth would anyone need to have a heartfelt conversation with themselves... And put it in a public place for others to read. It's only those narcissistic enough to think others might be interested in what they think.
Posting on a forum is a conversation between 2 or more people and meanders around as other participate.
The two are entirely different. Certainly you can see the difference.