I believe social media and social networks are synonymous terms, referring to a website that connects you to many people you may know, and some you may not, hence forming an online network. Examples of this would be Facebook, MySpace, and Twitter. Even though Twitter is considered “micro-blogging” it allows you to be much more “social” than a normal or typical blog. All of these examples allow users to converse freely, check out status updates, view photos, and more while everyone else is able to do the same about them. Users can examine deeply the life of another person (what they choose to share) and give feedback or become “social” over the site that is shared.
For that reason, I do not think blogs are social media. They are websites that one person controls and while others may sometimes be able to leave comments, there is no large conversation taking place. A blog author can choose to disable comments, truly taking away any aspect of socialization they might receive, and on top of that, they are not obligated to write back like users of social media websites, who are more or less are expected to. Blogs are much more one-sided than social media forms.