In addition to distinguishing between popular and scholarly articles, you need to be able to understand if the scholarly articles you are reading are reporting primary research or secondary research.
Primary research articles report original research and results. You will see the data and work that the authors produced. A primary source is an article that reports this. Other primary sources can include documents such as diaries and scrapbooks, photographs, and eyewitness accounts.
Secondary research often summarizes the work of many primary research studies. In the sciences, a common example of this is a review article. Review articles report and analyze the results of primary research articles, but don't report any new information.
Turbek, S. P., Chock, T. M., Donahue, K., Havrilla, C. A., Oliverio, A. M., Polutchko, S. K., Shoemaker, L. G. and Vimercati, L. (2016), Scientific Writing Made Easy: A Step-by-Step Guide to Undergraduate Writing in the Biological Sciences. Bull Ecol Soc Am, 97: 417–426. doi:10.1002/bes2.1258
Gopen, G., & Swan, J. (2018, January 3). The Science of Scientific Writing. Retrieved February 26, 2018, from https://www.americanscientist.org/blog/the-long-view/the-science-of-scientific-writing