To identify whether an article in a peer-reviewed journal is a primary research article, look for some internal clues:
Does the abstract indicate that an experimental study was performed? Does it mention "this study" or include phrases such as "measured," "compared," "determined," "found," etc.?
Does the article include a section describing the experimental methods that were followed?
Does the article include a section describing the experimental results, usually with data tables and figures?
These are all indications that an article is a primary research article ("primary" because the experiments were carried out by the researchers who wrote the article).
Literature reviews (also called review articles) are articles that summarize and synthesize primary research on a topic.
They are authored by experts in the field and are published in scholarly journals or as book chapters
They summarize multiple primary research articles
They are secondary literature
Literature reviews are a good starting point when researching a topic because they provide:
an overview of a particular area of study
extensive reference lists, which may be used to locate further relevant articles
ideas for narrowing a too-broad topic
Identifying literature reviews
There are several criteria that can help you to identify literature reviews:
Some databases (such as PubMed, Embase, Scopus, and Web of Science, but not Google Scholar) allow you to limit your search to literature reviews. Look at the Filters or Refine results menus on the search results pages.
Usually the database will label review articles as reviews somewhere in the full article record, or the article itself may say that it is a review.
The abstract or introduction to a literature review may state the authors' intention to survey or analyze the literature on a particular topic.
Literature reviews generally do not present original data (data that has not already been published elsewhere) or describe specific research methods in detail.
Note: Many primary research articles include a short section that summarizes pertinent scientific literature as background for the paper. This isn't the same thing as a literature review or review article, which is entirely devoted to a summary of primary articles.