The Peer-reviewed limit in Franklin Articles+ is derived from Peer-review indications in the Ulrich's Directory of Periodicals and will limit your search results to a majority of journal articles. If you select Peer-Reviewed, it will be "sticky" and stay checked until manually removed.
Regardless of whether or not the Peer-Review limit is applied, a peer-review indicator will appear next to each peer reviewed source. Under the Advanced Search, there is also a Peer reviewed publication only limit.
Below are definitions of academic/scholarly and peer-reviewed, as provided by Ulrich's:
Academic/Scholarly: A serial type assigned by Ulrich's to describe the primary audience for the publication. The Scholarly determination is made by a process combining publisher self-reporting about individual titles and independent Ulrich's editorial research.
Peer-Reviewed: The terms "peer-reviewed" refers to the system of critical evaluation of articles by professional colleagues or peers. Multiple types of peer-review (e.g., double-blind, expert) are included under this designation. The content of refereed publications is sanctioned, vetted, or otherwise approved by a peer-review or editorial board. Ulrich's gathers information about peer-reviewed publications from publishers. The information is supplemented by feedback from librarians and individuals associated with the publications, as well as through independent research conducted by the Ulrich's editorial team.