Comparing RDF files

Assuming you are using Jena as your tags suggest you can do the following:

Model diff = a.difference(b);

See the difference() method documentation for description of what exactly this returns.

If you just want to check whether they are the same or different:

Model.isIsomorphicWith

which works by trying to find does blank node isomorphism from one model to the other.

Full details: http://www.hpl.hp.com/techreports/2001/HPL-2001-293.pdf

If your RDF files represent valid OWL 2 ontologies, you can use the owl2diff tool from owl2vcs.

If you need to do it programmatically, the code is open source. The tool is based on OWL API.

Here is an example of what the tool produces. Not triples, but axioms.

$ owl2diff pizza14.owl pizza15.owl
* OntologyID(<http://www.co-ode.org/ontologies/pizza/pizza.owl>)
- Prefix(daml:=<http://www.daml.org/2001/03/daml+oil#>)
- Prefix(protege:=<http://protege.stanford.edu/plugins/owl/protege#>)
* Prefix(:=<http://www.co-ode.org/ontologies/pizza/2006/07/18/pizza.owl#> <http://www.co-ode.org/ontologies/pizza/pizza.owl#>)
- Prefix(dc:=<http://purl.org/dc/elements/1.1/>)
- Import(<http://protege.stanford.edu/plugins/owl/protege>)
- Annotation(protege:defaultLanguage "en"^^xsd:string)
- Annotation(owl:versionInfo "version 1.4"^^xsd:string)
+ Annotation(owl:versionInfo "version 1.5"^^xsd:string)
+ Annotation(owl:versionInfo "v.1.5. Removed protege.owl import and references. Made ontology URI date-independent"@en)
- AnnotationAssertion(rdfs:comment :SpicyPizzaEquivalent "An alternative definition for the SpicyPizza which does away with needing a definition of SpicyTopping and uses a slightly more complicated restriction: Pizzas that have at least one topping that is both a PizzaTopping and has spiciness hot are members of this class. "@en)
- AnnotationAssertion(rdfs:comment :VegetarianPizzaEquivalent2 "An alternative to VegetarianPizzaEquiv1 that does not require a definition of VegetarianTopping. Perhaps more difficult to maintain. Not equivalent to VegetarianPizza "@en)
- AnnotationAssertion(rdfs:label :GoatsCheeseTopping "CoberturaDeQueijoDeCabra  "@pt)
+ ClassAssertion(owl:Thing :France)
+ AnnotationAssertion(rdfs:comment :VegetarianPizzaEquivalent2 "An alternative to VegetarianPizzaEquiv1 that does not require a definition of VegetarianTopping. Perhaps more difficult to maintain. Not equivalent to VegetarianPizza"@en)
+ ClassAssertion(owl:Thing :England)
+ AnnotationAssertion(rdfs:comment :SpicyPizzaEquivalent "An alternative definition for the SpicyPizza which does away with needing a definition of SpicyTopping and uses a slightly more complicated restriction: Pizzas that have at least one topping that is both a PizzaTopping and has spiciness hot are members of this class."@en)
+ ClassAssertion(owl:Thing :Germany)
+ ClassAssertion(owl:Thing :America)
+ AnnotationAssertion(rdfs:label :GoatsCheeseTopping "CoberturaDeQueijoDeCabra"@pt)
+ ClassAssertion(owl:Thing :Italy)