Question

Can I achieve conversion of XML from one format to another using a SAX parser or a Transformer? If so, then what is the exact difference ?

EDIT:: I mean the transformer I create using SAXTransformerFactory

Answer 1

The SAX parser allows you to parse the XML document within Java. It will call you back for every element, character sequence etc. and using this you can construct a object tree representing some/all of the XML, or perform some other function.

Other types of parsers exist. A DOM parser will give you a tree-based object representation of the XML document. THere are pros/cons to each parser type (DOM is typically characterised as more-memory intensive, but providing a complete model of the XML, whereas SAX is lightweight but you’re called back by the parser itself and can’t navigate any model of the XML)

I’m a little vague wrt. your XML Transformer, but I assume you mean an XSLT. That’s a stylesheet transformation, and operates at a higher level, applying a transformation (stylesheet) to the input XML and giving an output (usually, but not limited to, XML)

EDIT: Following your comment, see this article:

Finally you probably want to write the xml document to a string or to
a file, this can be done with a Transformer object, which come from
the transformer factory