Scholarly articles are found in journals. These articles are usually lengthy and written in scholarly language by scholars and researchers. The articles are frequently peer-reviewed, which means that the information in the article was checked for accuracy and importance by a team of experts in the field before publication.
Scholarly articles often report on research. Research articles can be identified by their standard format, containing sections titled Methods, Results, Conclusions, and Bibliography.
Be aware that scholarly journals often contain review articles about new books or resources as well as editorial opinion articles. While these articles can be useful they do not qualify as "scholarly" or "peer-reviewed".
Popular articles are the articles in magazines that you encounter in the grocery store or the dentist's office. The articles are written by journalists to inform and entertain, and frequently give short, easy-to-read overviews of the research articles published in scholarly journals.
A third type of journal article you might encounter is a trade journal article. These articles contain practical advice and information for workers within a specific trade. A professional pharmacist might read the trade journal U.S. Pharmacist to find out about new advances in child-proof lids but she will still turn to scholarly research articles to learn how a new drug performed in clinical trials.