Hey Vladimir,
1503 is the second release of Sfin / S/4 HANA Finance by SAP also called as SFIN 2.0
It had a lot of changes and new features in Finance area.
The 1503 release of S/4 HANA had mainly changes in FICO area and the main migration was involved for Finance and controlling related elements.
Now the next release 1508 was also for Financials solution and if you are in 1503 already , there is not much of migration involved.
The next release 1511 has a lot of changes. This release has SAP Simple Logistics solutions.
This has changes in a lot of area like master data ( BP being mandatory for Vendors- Customer etc), in Material management ( new table structure for MM data) and also changes in FICO ( a lot of changes in Asset Accounting)
So if you are moving to 1511 there will a good migration effort and it will be across modules.
Do read about this in help.sap to decide the path.
Hope this helps,
Please close the thread.
Regards
Rishab