When you are writing a literature review you need to do more than just describe what has been found or what people have said. Your writing needs to be critical. It needs to go beyond being descriptive, analytical and persuasive.
This article from the Learning Centre at The University of Sydney gives a great explanation of what these different types of academic writing entail. http://sydney.edu.au/stuserv/learning_centre/help/analysing/an_distinguishTypes.shtml