ABAP code comparision
Can ABAP code be compared between previous versions and across instances..?
Yes. different versions of ABAP code can be compared against each other in the same instance/client and also across instances.
For comparing code between different versions on the same instance, do the following
1. SE38
2. Enter the program name
3. Utilities-> Versions -> Version management
4. checkmark the 2 versions that need to be compared.
5. F8.

For comparing code between versions on different instances , do the following.
1. SE39
2. enter the name of the programs that need to be compared across instances.
3. click on "compare different systems" button on the top
4. Enter the RFC destination of the 2nd program. (if required login)