Scholarly (aka academic) articles are written by and for academics, researchers, and experts in the specific topic or broader subject area of the article. Typically involves commercial or professional association publishers.
Peer reviewed (aka refereed) articles are those scholarly articles which have been reviewed prior to publication by other experts in the topic of the article. Often reviewers are external (not members of the journal's editorial staff or board).
Grey literature is material of a scholarly nature produced outside the usual publication channels. Grey literature can include government publications, think tank reports, conference proceedings, studies from nongovernmental organizations (NGOs), evaluation reports, technical reports, etc.
Grey literature can be harder to identify and find because it often isn't formally published and is less frequently indexed in the databases used to find scholarly literature, although some databases do include some grey literature. Searching online, identifying likely producers of grey literature, and checking lists of references in books or articles are ways to help identify grey literature.
Articles delivered electronically generally arrive in 1-3 days
Print materials to be loaned out generally arrive in 2-10 days