XML AND JOSN DIFFER

http://stereolambda.com/2010/03/19/why-is-json-so-popular-developers-want-out-of-the-syntax-business/

Without wanting to dispute the relative merits of JSON (which I know very little about) and XML, I would say that XML is extremely good for automatic treatment, information exchanges between different applications, and similar—but is simply not constructed for intense user/developer interaction.
The fact that it is human readable and editable is a clear bonus, but can mislead people to think that it is something they should work directly with. XML, IMO, belongs further down the abstraction hierarchy where it rarely encounters any human. (Obviously, library developers and the like will eventually have to deal directly with it.)
A very obvious parallel is HTML: When I am allowed to choose (not always the case) webdevelopment directly in HTML is the exception and most HTML is generated through other types of document descriptions, say a basic markup language (as known from e.g. Wikipedia) or through JSP-style tag libraries. (This comment should not in anyway be seen as a recommendation of WYSIWYG HTML-editors—that is a very different topic.)

WHAT DOES SOAP,XML,JSON

JSON is a standard to represent human-readable data. It merely represents data, nothing more.
SOAP is a protocol specification for transmiting information and calling web services, and uses XML to encode it. SOAP works over HTTP (amogst other network protocols).
XML-RPC is another protocol, used for transmiting information and calling remote procedures. It doesn't run over HTTP, but is rather a different protocol, different port, etc.
So the main difference between SOAP and XML-RPC that the former wraps inside HTTP, while the latter does not. JSON is something completely different.