Oh dear, you are very confused.
<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/TR/WD-xsl"
defines a variant of XSLT introduced by Microsoft in 1998 before the XSLT 1.0 specs were finished in 1999. It is very rarely seen nowadays, and is not documented or supported, although I believe it still runs in Internet Explorer.
identifies a draft of the XSLT 2.0 recommendation (not the final version).
You need to decide which version of XSLT you are trying to use.
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference