1) Export from the 10.2.0.2.0 version database with below command:
$expdp system/********* directory=data_pump_dir dumpfile=full_db_exp.dmp logfile=full_db_exp.log full=y version=10.1.0.1.0
2) Import the dumpfile (10.2.0.2.0 version) to the 10.1.0.1.0 database:
$impdp system/******** directory=data_pump_dir dumpfile=full_db_exp.dmp logfile=full_db_imp.log full=y
