JSON Pro :
* Simple syntax, which results in less "markup" overhead compared to XML.
* Easy to use with JavaScript as the markup is a subset of JS object literal notation and has the same basic data types as JavaScript.
* JSON Schema for description and datatype and structure validation
* JsonPath for extracting information in deeply nested structures
JSON Con :
* Simple syntax, only a handful of different data types are supported.
* No support for comments.
XML Pro :
* Generalized markup; it is possible to create "dialects" for any kind of purpose
* XML deals remarkably well with the full richness of unstructured data CDATA
* XML Schema for datatype, structure validation. Makes it also possible to create new datatypes
* XSLT for transformation into different output formats
* XPath/XQuery for extracting information in deeply nested structures
* built in support for namespaces
XML Con :
* Relatively wordy compared to JSON (results in more data for the same amount of information).
* XML presents a 21% overhead over JSON
* Requires some reasonable more time to compress.
