OWL Questions!

Hi,
I'm an italian student of computer science and I'm interesting in Web Ontology Language. 
I read documents about it, but i didn't understand well how OWL works and the relation with RDFS.... here some questions

1) OWL is an extension of RDFS? That is, OWL has much expressive power than RDFS ( i can express thing that with RDFS i coudn't ) or it's equal but it can express relation and properties more easily? 

2)There are some pratical example of the use and usefulness of OWL? ( Not test cases of W3C or Wine ontology)
   I think to a tool that can do something usefull with an ontology.... 

I think that without some very pratical example people cound't understand well how ontology work and why develop them. Thanks for any answer... and sorry for my english! ;-)
Davide.

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Davide Noaro 
noarodavide@libero.it
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