If all you need is to compare two schemas entirely, you can use DBMS_RECTIFIER_DIFF package against data dictionary objects on the schema level such as USER_TABLES, USER_INDEXES, USER_TAB_COLUMNS, etc...

If it does not work againt data dictionary views (that is possible), you can put together a simple script to take a snapshot from them into a set of tables and compare them.

Good luck,
Sergey Popov
Sr. Oracle DBA
Bank of America