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.
Sr. Oracle DBA
Bank of America
I've just took a shower and got a minor correction in the process. You should take a snapshot from the data dictionary views no matter what otherwise you will get an incorrect result because of statistics difference in the views. In additional to that these views are created on several base tables and will work slower on comparrison itself. So, take snapshots, get only columns you need and go ahead with DBMS_RECTIFIER_DIFF.
PS: I need to move my desk to the shower. I get most of my ideas in there