The literature you will read about Systematic Reviews includes specific vocabulary. Here are some of the most common terms defined in the context of Systematic Reviews:
Bias - a systematic distortion of an estimated effect.
Primary Studies - An original piece of research where the author generates new data by running a new experiment, or by collecting original data from patients. Randomized Controlled Trials are examples of primary studies. In contrast a synthetic study does not generate new data, but combines results from several primary studies using meta-analysis or meta-synthesis.
Qualitative research - Research providing detailed narrative descriptions and explanations of phenomena investigated, with lesser emphasis given to numerical quantifications -- methods used to collect qualitative data include ethnographic practices such as observing and interviewing.
Quantitative Research - Application of statistical processes and theory to the compilation, presentation, discussion, and interpretation of numerical data.