Structure definition and capable statement enigma

[Francesco Docimo]

Hi

we need to create a subset of resource (e.g. meta without patient) and as I know I can use structureDefinition resource .

These are my question : what is the purpose of capableStatement ?
what is the difference between capableStatement and structureDefinition?
If I put more than one capabiltiy statement inside hapi fhir , are the resource affected by the particular CapableStatement loaded in ? How can I use one of the capableStatement loaded into hapiFhir ?
Thank in advance

Francesco