Sarah's answer is good. I would add two notes. If the annotated bibliography is for an academic paper or is a scholarly tool, then every item gets a note (is annotated), not just some of them. For a college or graduate school assignment, you would describe each work, but not make a recommendation. In a published scholarly annotated bibliography, the note always describes the item, and may also recommend how it can be used. A published scholarly annotated bibliography can be an article in itself, or added to article, or included in a book
Also, in more informal and practical works, such as business books or articles, an annotated bibliography might be called "suggested reading" or "recommended reading."
The term "bibliography" traditionally refers to books, and "discography" to records or music, but, these days a bibliography can cite sources on the Internet, as well.