posted 12 years ago
When you export the data using EXP, the EXP process connects to the database, reads the data and writes them to some directory on a machine on which it runs.
When you're using EXPDP, the export process actually runs in the database, EXPDP is just a program which configures and starts the process (you can configure and start the export processes using some DBMS packages via PL/SQL, you don't actually need the EXPDP executable). The dump can be created only in directories configured in the database (see CREATE DIRECTORY), that is directories the DB server can see.
In both cases, you can use network drives/connections to access the dump. With EXP, you can always access the dump file from the machine you've run run the EXP on. However, if you run EXPDP on a machine which cannot directly see directories the DB server can see, you may have trouble accessing the dump files. This can be troublesome in more restricted environments.