Google Scholar does not include all of the content contained in library databases. However, there is some content overlap. Often you'll find that in order to access the full-text of resources you find in Google Scholar, you'll need to click on a link that lets you access it via your home library. For example, you may see a link that says "Full-Text Options at SLU." Clicking on it will take you into a SLU library database. If you weren't affiliated with SLU, you wouldn't have access to that content.
In addition to the difference in content, library databases offer more options for searching and limiting results in different ways.
Even though Google Scholar doesn't include as much content as library databases and has more limited search functionality, you can still use it to find a lot of scholarly information. Our advice would be to search Google Scholar IN ADDITION to library databases. That way you'll make sure you're not missing out on information that could be important to your research.
If you'd like help developing a research strategy, please ask a librarian.