Whats the difference?

Hi all,
I only just discovered Piwik and I have to say it looks absolutely marvellous. I run a number of Wordpress blogs and I believe that I can install Piwik in them…correct?
But my main question concerns the use of Piwik in static sites like this one

But…what actually is the main advantage over Google analytics that Piwik offers?
Is there an opportunity to see what traffic comes from which search engine?

Thanks in advance.

Ahch…sorry, just answered my own question if I had visited the FAQS first. Sorry. If admin wants to delete please feel free.