Q: What should I use to look up books in the library?
A: Both will work!
USearch is the main search box on the library homepage and will show you relevance-ranked results (similar to a Google search). When you use USearch, you're actually searching within the Catalogue as well as many of our online databases at the same time. USearch is useful when you want to start off with a broad search and then narrow down your results as needed. Those results could include books, journal articles, and much more. You're more likely to get hundreds or even thousands of different results.
The Catalogue is a searchable index listing everything the library has purchased or licensed, including all print material. It might be easier to use the Catalogue if...
The Which search tool should I use? page has more details about which search tool to use when.