Definition time. I need help.

If someone intends to have a commerce website, and they want to have a space upon it where people can post travel pictures and talk about things, I think of that as a forum, not a blog. A blog, as I understand it, is where one person talks about something with regular posts and/or pictures, but not where other people can chime in too.

The intent of this one is not for the site owner to be doing much/any authoring. What is it I'm picturing?

Obviously you can have a more blog-like structure but allow multiple people to post. It might be a question of traffic--if only a few people are expected to post, that might work fine. Otherwise, things will disappear off of the front page almost instantly, and a forum would work better. But you could easily do a hybrid of the two.