From OWL Purdue:
A bibliography is a list of sources (books, journals, Web sites, periodicals, etc.) one has used for researching a topic. Bibliographies are sometimes called "References" or "Works Cited" depending on the style format you are using. A bibliography usually just includes the bibliographic information (i.e., the author, title, publisher, etc.).
An annotation is a summary and/or evaluation. Therefore, an annotated bibliography includes a summary and/or evaluation of each of the sources. Depending on your project or the assignment, your annotations may do one or more of the following.
What are the research methods, if any, employed in the source?
Does the author cite other research? Is there a bibliography? Footnotes?
Have other scholars cited the information source?
Does the work succeed?
How is it useful to me or others?
What are the author’s affiliations?
What are the author’s goals & objectives?
When the information was created or last updated?
Is the date important for the timeliness of the content?