For me, a forum consists of different thread, with different sub thread that contains lots of topics. The topics are categorize and there are admins, SEO, Quality Creator and Owner always updating the site.They have members who are active in making the post or starting a topic. Blog, on the other hand, is maintained by a person or two. The owner itself could work as a SEO content giver, admin and everything, even the social media manager. Blog contains different topics or articles that everyone could leave a comment on some blogs. Both of the sites need SEO and active posting. I am not a technical person but I can describe Blog as something personal compare to Forums. Forums, are a site that is active and entertaining. I am a member of blogging sites and forum sites and I can say, I love both.