"Scholarly Journal" and "Academic Journal" are two words for the same thing. Scholarly journals publish articles—usually articles about research—written by experts (scholars) in the field of study.
Usually, articles in these publications go through a "peer-review" process, which means other experts (peers) weigh in on the quality of the article and the research it presents as well as the article's importance in their field of study. Many professors will require you to use scholarly sources because they are more credible than articles published in popular magazines or on most websites.
Many databases label articles as scholarly or popular so it's easy to tell the difference from a quick glance.
For more help, ask a librarian.
