A literature review is a survey and critical analysis of what has been written on a particular topic, theory, question or method.
What's its purpose?
Original research
Original research articles are based on an experiment or a study of a topic. They include a methodology section if an experiment was set up and conducted, a results or discussion section, and a conclusion.
Review articles
Review articles are written to bring together and summarise the results or conclusions from many original research articles or studies. They do not usually contain a methodology section, but they will contain very extensive bibliographies.
An annotated bibliography provides: