A research article is a primary source.
It reports the methods and results of an original study. The authors collect and analyze raw data and draw conclusions from the results of that analysis.
Research papers follow a particular format. They include:
An introduction: This will often include a review of the existing literature on the topic and explain the rationale of the authors’ study. It demonstrates that the authors are aware of existing studies and are planning to contribute to this existing body of research.
A methods section: The authors describe how they collected and analyzed data. Statistical analyses are included.
A results section: This describes the outcomes of the data analysis. Charts and graphs illustrating the results are typically included.
A discussion: The authors explain their results and theorize on their importance to existing and future research.
References: This is a list of sources that the authors used to plan their study and support their discussion.
A review article is a secondary source.
A secondary source is one step removed from the original source (the research article). It reviews primary sources and does not present original research of its own. The review article reexamines, interprets and forms conclusions based on the information that is conveyed in the primary source. Review articles can suggest areas for new research, or identify patterns among existing research.