"That's a clown question, bro" - - - - - - - - - - Bryce Harper, DC Statesman "But Oz never did give nothing to the Tin Man That he didn't, didn't already have" - - - - - - - - - - Dewey Bunnell, America
They are very similar in nature. A blog is basically an article written as an opinion. Otherwise known as a long post.
RIP 21
"Nah, I trust the laws of nature to stay constant. I don't pray that the sun will rise tomorrow, and I don't need to pray that someone will beat the Cowboys in the playoffs." - Irn-Bru
As far as this site goes, blogs are published on the main page (as a kind of casual, mini-article), and the forum exists so that people can comment on them as if they were regular threads on the board.
Outside of this board, tons of blogs exist for all different kinds of purposes. (Political, personal, for photos, interesting or specialized news, etc.)