I don't think the exam will ask you to make this distinction. The important thing is that you cannot use keywords or literals as identifiers. For example, you cannot declare a variable like int goto = 7;
Well, the exam wont test you on this. But, technically "true", "false" and "null" are literals and not keywords. But there is not much of a distinction in practice(of course the usage is different but you cant declare int true=1). Check the JLS.