1) A systematic review is a summary of research that addresses a focused clinical question in a systematic, reproducible manner.
A systematic review is often accompanied by a meta-analysis (a statistical pooling or aggregation of results from different studies) to provide a single best estimate of effect. The pooling of studies increases precision (ie, narrows the confidence intervals [CIs]), and the single best effect estimate generated facilitates clinical decision making.
Guyatt, G., Rennie, D., Evidence-Based Medicine Working Group, & American Medical Association. (2015). The process of a systematic review and meta-analysis. In Users' guides to the medical literature: A manual for evidence-based clinical practice (3rd ed.). Chicago, IL: AMA Press.
2) Systematic review: The application of strategies that limit bias in the assembly, critical appraisal, and synthesis of all relevant studies on a specific topic. Systematic reviews focus on peer-reviewed publications about a specific health problem and use rigorous, standardized methods for selecting and assessing articles. A systematic review may or may not include a meta-analysis, which is a quantitative summary of the results.
Last, J. M. (2001). A dictionary of epidemiology (4th ed.). Retrieved from http://www.cebm.net/glossary/