Oracle apps is a ERP package which is made up using the software primarily oracle as a backend and d2k as a front end.

Oracle apps reports are same as D2k reports.Only thing is they use exits(specifically defined for ERP) and use them in report.

D2K reports and Oracle Reports basically have no difference the main
difference between them is only that simple D2k report run in any environment
and we always use Tables if we want to run a report in D2K

But if we want to run any Oracle Report then we need an environment which is
given by an pre-defined function "USER EXIT" which is used in Oracle. USER EXIT
gives an environment for D2K Connect to Oracle APPS and if we use this function
then we need to pass a parameter named "P_CONC_REQUEST_ID" in "FND SRWINIT" USER
EXIT .

USER EXIT is of five types

1. FND SRWINIT


2. FND SRWEXIT


3. FND FORMAT_CURRENCY


4. FND FLEXIDVAL


5. FND FLEXSQL

All perform there different different work as there functionality.