What's the difference between Google Scholar and an academic database like Engineering Village or Business Source Ultimate?

Academic databases are searchable collections of published sources that let you know exactly what books, journals, conferences, etc...they are pulling their content from. In many databases, you can easily find a list of publications they are pulling citations from. That means you can tell if you'll be able to find articles from Nature in the database or not. Additionally, academic databases frequently have a subject specific focus and have many options for limiting search results.

Google scholar is also a searchable collection of published sources, but because Google keeps their proprietary information private, they do not share where they are pulling their content from. We don't know exactly where the citations are coming from, what will be included, or what might be missing. Additionally, Google Scholar covers all disciplines and only has a few advanced search options.

Google Scholar is good for...

• Helping a beginning researcher identify journal titles and authors connected with subjects of interest.
• Finding "gray literature" like conference proceedings. It includes many articles that wouldn't get included in other indexing services.
• Locating obscure references that are proving difficult to find in conventional databases.
• Locating more information on partial citations.

Google Scholar cannot...

• Sort/search by disciplinary field
• Browse by title
• Limit search results
• Search the deep web

Keep in Mind:

• You may get a long list of results, but you will only have access to the text of articles that the University of Illinois Library has paid subscriptions for, or that are freely available.
• Not everything in Google Scholar is scholarly. Google Scholar searches academic websites (.edu) as well as journals and publisher websites. Search results can include PowerPoints, news announcements or unpublished materials as well as articles and books. 
• Searching in Google Scholar is imprecise when compared with discipline-specific databases.

Google Scholar searches specifically for scholarly materials such as journal articles, research reports, dissertations and theses, preprints, technical reports, patents, manuscripts in preparation, working papers and many other document types.

When you do a search in Google Scholar, you get a list of citations. You'll get links to the full text in the following cases:

• If the Illinois library subscribes to the journal title
• If it's from an open access journal
• If the researcher posted the article on her/his website.

We don't know exactly how Google Scholar indexes items, but this is how Google Scholar defines its metrics.