1->XML Properties:
a) With XML, it is illegal to omit the closing tag.
b) Unlike HTML, XML tags are case sensitive.
c) Improper nesting of tags makes no sense to XML.
d) All XML documents must contain a single tag pair to define a root element.
e) With XML, it is illegal to omit quotation marks around attribute values.
f) With XML, the white space in your document is not truncated.
g) With XML, a new line is always stored as LF.
h) Comments in XML

2->XSL consists of three parts:

http://www.w3schools.com/xpath/xpath1.gif

XSLT – a language for transforming XML documents
XPath – a language for navigating in XML documents

XSL-FO – a language for formatting XML documents