One of the primary reasons why XML was created in the nineties was that it allowed open data sharing by providing an interchangeable data serialization format. It was able to handle native data types and also other formats such as images, audio, documents and so on.

While it is possible to attach any file format to an XML message, JSON on the other hand, only supports simple data structures stored as arrays. Both formats have their advantages, but data transfers will be easier and faster if the data serialization resembles the structure of the data it represents. JSON makes it very easy to import the data into languages such as JavaScript, Ruby, Python, and many others.

XML is the ideal format for transferring documents as it can be used to define the structure or format of the data along with the actual data. When returning XML, it should be without the namespaces present.

JSON is best used for data sharing as it is only suitable for transferring the data component.