tables in html? (separating content bla bla)

Maybe in html 8 or xhtml 21, please clean up table model, maybe do two
type of table: data_table and, if necessary and yes is necessary,
layout_table.
In another life, maybe, clarify structure concept and definition.
example: <http://www.tiuvizeta.it/abstract_document.jpg>
What is structure? titolo1 or h1?

ciao
Livio Mondini