"A summary of the clinical literature. A systematic review is a critical assessment and evaluation of all research studies that address a particular clinical issue. The researchers use an organized method of locating, assembling, and evaluating a body of literature on a particular topic using a set of specific criteria. A systematic review typically includes a description of the findings of the collection of research studies. The systematic review may also include a quantitative pooling of data, called a meta-analysis" -taken from the Agency for Healthcare Research and Quality Glossary (no longer online).
"A way of combining data from many different research studies. A meta-analysis is a statistical process that combines the findings from individual studies" -taken from the Agency for Healthcare Research and Quality Glossary (no longer online).
Image from TeachEPI.org
There are many other types of study designs or research designs. You can learn more by following the links below.