A subject search can be different than a keyword search. Subject is usually shorthand for the library-speak term Library of Congress Subject Heading, which basically means controlled-vocabulary term. For example, libraries use the term capital punishment, rather than death penalty, to classify their materials on the topic.
A keyword can be a natural-language term. In an online library setting, a keyword search will generally look for the term in the entire document, including the title and the body of the article.
Scholarly=peer-reviewed=refereed=academic. What does it all mean? See our online guide detailing the important differences between popular (magazines and newspapers) and scholarly (journal) resources.