Oracle Server = Oracle Instance + Oracle Database Oracle instance comprises of Background Process and memory structures in Unix all background processes are treated as independent processes but in windows all are combined together within oracle.exe in unix when a user logins he is dedicated to the server via an independed process so if require you can kill a process through os level ..this is one of the major advantage of using oracle on unix based system rather then windows system bcoz in case database stucks or hangs an independent process causing the problem can be killed and database will be made resumable immediately.

and one more diffrence is in windows you are require to create a service to start the instance by using oradim but in unix its not required .you can start the instance.in windows unique service name is required but in unix diffrent user can have the same service name started by them but its not advisable.

Regards

Ritesh Raj Singh

Database Administration Team

ICICI Ltd

Mumbai