Within the Blog Posts Module you can add, edit, and delete your Blog Posts. Regardless of Blog; all Blog Posts will reside here.
The Blogs Module houses the information for all of your Blogs. This is where you edit the information for a Blog as a whole. You can click on the latest Post, as well as set your comment notification email.
The Categories Module houses the Categories for your Blogs. Categories give you the ability to parse Blog Posts based on Category.
The Authors Module allows you to Add, Edit and Delete Authors for your Blog Posts. It is a straightforward Module, simply listing Authors that have already been created