The RDF data model is fundamentally different from XML.

XML uses elements and attributes
RDF uses nodes and relations.
XML Schema talks about data types.
- simple types: int, string, boolean, date, time...
- complex types: Address Record, Person Record
RDF Schema provides simple but useful rules.
if X is the father of Y, X is the parent of Y.
OWL provides more complex rules.
if X has a child that is a kitten, X is a cat.