In the beginning, when the blogosphere was in its infancy, blogs were usually hosted on a single domain. This type of blog is called a "single-domain blog" or "single-site blog."
The next type of blog is called a "multi-domain blog." In this kind of blog, the content is spread across multiple domains. The main difference between this and a single-domain site is that each domain has its own set of pages and posts. For example, in a multi-domain site you might have one domain for your homepage and another for your articles.
The third type of blog is called a "multi-author blog." In this kind of site there are multiple authors writing posts on the same topic from different perspectives.