Systematic Reviews - Usually focus on a clinical topic and answer a specific question. Extensive literature searches are conducted to identify studies with sound methodology. The studies are reviewed, assessed, and summarized according to the predetermined criteria of the review question.
Meta-analysis takes the Systematic Review a step further by using statistical techniques which summarize the results of several studies into a single estimate of their combined result.
Practice Guidelines are systematically developed statements that assist practitioners and patients when making decisions about appropriate health care for specific clinical circumstances. Guidelines review and evaluate the evidence and then make explicit recommendations for practice.
descriptions from Introduction to Health Services Research: A Self-Study Course. http://www.nlm.nih.gov/nichsr/ihcm/index.html