At times, professors will require that you use articles from scholarly journals instead of magazines. So you need to know how to distinguish between these two types of publications. There is a third type of periodical, the "trade publication" (also know as "trade journals") that fall between magazines and journals, that you must know about also.
Another distinction which professors will make between sources used in research is that of "primary" and "secondary" sources.
Primary sources are documents and other kinds of things, including objects, from the time period being studied. The Journals of the Lewis & Clark Expedition would be a primary source because they give eye-witness testimony regarding the events of the journey by the leaders of the expedition.
Autobiographies, diaries, speeches, interviews, government reports, contemporary news accounts, articles presenting original research, original photographs
Secondary sources comment on, interpret, or analyze information found in primary sources.
Books about a topic, literary criticism, book reviews, biographies