I think Arieanna that you are right. As I always say, Flickr is *social* photo blogging. Tags, photonotes and lots of little affordances on Flickr like the fact that you can easily see who has commented on or made one of your photos a favourite, the fact that there are RSS feeds for everything, etc. make it much more social than a normal blog.
One crucial difference between blogs and Flickr may be the cornerstone to this mystery. With Flickr, you have the ability to add notes, comments, and tags to photos. On Flickr, you can add a comment to any part of the photo; you can also tag a photo (yours or someone else's) to assign it to that keyword category. Since the tags are searchable, your photos are always coming up and being viewed by others - no matter when you took it. So, people are interacting with the photo in a way not otherwise possible. This creates an ongoing conversation about the photo and the fluidity of its meaning, constantly revising where it belongs in the taxonomy. And, perhaps as importantly, this interaction amongst the Flickr community gives one a sense of contributing to an overall archive of shared experiences.
What do you think?