Why XSLT is better than HTML??.Is there any seo advantages for XSLT deisgns??

XSLT is TOTALLY different to HTML

XSLT is a separate markup language for transforming XML documents to (X)HTML

Is there any seo advantages for XSLT deisgns

Absolutely none. Most bots are not XSLT capable so will only read the XML nodes

As chris said, but I just wanted to add that XSL is not just to transform XML to (x)html, but to transform it into another XML, or plain text, or even PDF (via XSL-FO).

I use it all the time, because I receive an XML file that I must transform into another structure and clean up irrelevant datas (a sales report from several providers, where I must display only the values of the logged user) , and I do it via XSL.

It's a 2 steps process.
1st to have a "splitted" version of the initial file, and the second time to transform the splitted XML into html.

Here are a couple of really simple xslt transformations.
These take an XML file, and by using the transformation engine built into most browsers, convert it to HTML using a simple XSLT.

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