> I am trying to copy the data in an existing FDB to another FDB.
> The database schema varies for both the databases.
>
> Please suggest me any tool which copies the data into the destination
> FDB, with out changing the schema.
>
> Also consider if the source FDB has some data in the columns.
>
> If that particular columns doesnot exist in the destination FDB, then
> what will be the behavior of the tool?

You probably want to look at a data pumping tool. Firebird website
links to IBPhoenix which maintains a list.
http://www.ibphoenix.com/main.nfs?a=ibphoenix&s=1188522074:1351386&page=ibp_mig_tools

I have used Interbase DataPump and FBExport (and FBCopy). The best one
really depends on what you want to do. Most have configurable behaviour.

Adam