Hi Vikas,
difference between latest EHP3 and EHP4 is the Netweaver version.
If you are interested in the latest capabilities of Netweaver 7.50, go to EHP4.
From a functional point of view, not so many more possibilities yet in EHP4 compared to EHP3
As stated in SAP slide hereby: likely decision drive = your preferred NW version in overall SAP landscape
Regards,
Bart