This paper will attempt an objective side-by-side comparison of the two languages: not just from the point of view of technical features, but also looking at usability, vendor support, performance, portability, and other decision factors. Is it true, for example, that XQuery is better for data and XSLT is better for documents? Is one or the other language easier to learn depending on your computing background? As well as trying to answer these questions, the paper will also illustrate how the two languages can interoperate, so that each can be used for the parts of an application where it is most appropriate.