In SQL Developer, under the "Tools" menu, there is an option "Database Diff". It produces a report of the differences between objects in two different Oracle schema. It then allows you to generate SQL to implement the changes necessary to make the 'Target' schema objects match the 'Source' schema objects. This SQL does not include grants. I request that grants be included, at least in those objects (like materialized views) that are dropped and recreated.
Archived, please refer to this ER in the SQL Developer Exchange instead.