There is no need for two platforms as both the 60R & 70B perform virtually the same ASW & ASuW missions.
In addition, the MH-60R is not in the current tender for 16 MRH aircraft for the Indian navy. The S-70B is & should win that competition. The Indian Navy, I believe, will be happy with that choice and it would then make no sense to procure another aircraft for the obvious reasons (training, maintenance, logistics, etc.) The S-70B can also be configured in a utility version to offer the same capabilities as the MH-60S.
As far as major differences:
1. S-70B has the Penguin Anti-Ship missile already integrated, the 60R does not.
2. Both have the American MK-46 & MK-54 torpedoes already integrated. The 70B also has the Eurotorp A244 mod 3 torpedo integrated.
3. The 70B AFCS is a new system that represents a significant improvement over earlier Seahawk systems.
4. The new WMS facilitates integration of indigenous systems or unique customer required stores or weapons.
5. The 70B employs a "federated systems architecture" meaning major functions are dispersed to centralized subsystems. Modification enhancement has typically proved to be easier, cheaper, and less risk for systems of this type, while the 60R employs a "centralized architecture" with a primary and backup mission computer that performs all mission related functions ( mission management, flight management, weapons management, navigation, etc.)
6. Both have integrated FLIR, ESM, counter measures, Radar, EGI (embedded GPS with inertial) navigation and attitude reference systems, and AFCS systems. I believe the 60R does not currently have a VOR/TACAN navigation capability.
7. The mission and avionics systems for the 70B are designed and tested by Sikorsky Aircraft. The 60R systems are done by Lockheed Martin. Sikorsky makes both airframes. My opinion is that Sikorsky has fielded a greatly superior avionics & mission system in the 70B.
For this reader, the S-70B is the clear choice.