What is a systematic review compared to a meta-analysis?

A systematic review is a systematic collection of literature with pre-defined data extraction and a so-called qualitative synthesis that is a reporting of the combined results in text format in a scientific paper.

A meta-analysis can be regarded as an add-on to a systematic review, where the meta-analysis provides a quantitative data synthesis. In other words the meta-analysis will combine the results from the different papers found in the systematic review using special statistical methods and thereby the meta-analysis gives an overall estimate of the effect of a given intervention by combining data from multiple articles.