Database Refactoring

have been given two Data models, for the sake of simplicity let me call these models A and B. Now each of these models have a bunch of tables and preexisting relationships. Both of these models try to solve the same basic problem. Now my task is to refactor Data Model B into something closely resembling Data Model A. So in layman's terms, Data Model B should look like Data Model A while incorporating the additional tables that are essential to drive the application that uses Data Model A.
What would be the most effecient way of going through this process knowing the fact that Model B has close to 75 tables and Model A has 63 tables. There is no similarity in the naming conventions between these two tables. And the relationships between the tables of these two models differs as well.

Any help will be appreciated.

sounds like you have to go through each table and figure out what data each table holds (place suitable comments against the table for easier remembering) and then scheme up a plan so that you can match table against table. i'd do this using large pieces of paper.

good luck