Firstly, they are completely different from peer reviewed journals.
Review articles are usually written by one or more writers to summarize all the research, past and present on a particular topic. It involves searching everything relevant to the topic and organising it into a logical sequence.
Review articles usually involve an abstract (the same as a research article),background information on the topic, past and current available data, future researches, results and conclusions formed. Citing references is extremely important to a review article because they not only clear all charges of plagiarism, thus establishing credibility of the author, but also help lay down a strong foundation for the work.
Review Articles help one learn about the main people working in a given field, recent major advances and discoveries, significant gaps in the research,current debates and ideas of where research might go next.