If you ever wondered what's the difference between ALL_TABLES and ALL_ALL_TABLES then here's the answer: both views provide all tables to which the current user has access to but, in addition to the tables returned by ALL_TABLES, the ALL_ALL_TABLES will also return all object tables (system generated or not) accessible by the current user.
Pay attention that this may be an interview question (e.g. how can you get all tables you have access to?) and you may leave a good impression if you respond with another question: "Do you also want object tables to be included?". :)