A primary article will contain original research on a topic.
This type of article, sometimes called a secondary article, will summarize the research done on a certain topic.
Peer review is the process by which articles are selected for publication in academic/scholarly journals. The articles are evaluated for accuracy, proper research methodology, and the correct interpretation and use of data by other experts in the field. No other publications undergo this level of vetting.
If you are looking for peer reviewed articles, there are a number of ways to locate them. One way is to limit your database searches to only articles in peer reviewed publications. Many databases allow you to do this. For example, most EBSCO Host databases have a box labeled "Scholarly" or "Peer Reviewed" in the limiters section under the main search boxes.
Another way is to use Ulrich's Periodicals Directory. This is an authoritative source for information about periodicals. Simply search the title of the journal using a title (keyword) search in the search box ont he top right of the page. If the journal is labeled as refereed: yes (or has a little icon of a referee's jersey in the results list) then it is a peer reviewed publication.
These databases contain information on the technical aspects of video game development, design, and computer graphics in general.
The education databases are a good source for research on any topic related to children, youth, adolescents or college-age adults. From a gaming perspective, these databases are a good source of information on learning though games. They also have information on the effects of excessive game playing on children and adolescents.