Scholarly articles are not always peer-reviewed; peer-reviewed articles are always scholarly.
An article can be both scholarly and peer-reviewed; it can be only scholarly; but it cannot be peer-reviewed without being scholarly.
Scholarly articles, also known as "academic articles," are written by experts in a discipline, and include citations. Their content focuses on research or original analyses, and they are professional in appearance, with no advertisements or unrelated images. Publication requires the approval of an editorial board.
Peer-reviewed articles are scholarly articles that have undergone a highly-critical and rigorous review process by other scholars in the author's discipline, prior to publication. This process ensures that the article genuinely advances understanding in its field of study, that its research is valid, and that its conclusions match the research data cited within it.
Primary sources are first-hand or contemporary accounts of an event or topic. They enable the researcher to get as close as possible to what actually happened during a historical event or time period.
Secondary sources add interpretation, analysis, or commentary to an event or phenomenon covered by primary sources.