What's the Difference between shunt battery charger and battery protection IC?
Yes you would need both in a battery pack and external charger.

The protection IC is one per cell with 2 external Complementary FETs to provide perfect active balancing and protection from overcharge /current etc for parallel cells but not series cell balancing. It adds cost but adds law suit avoidance protection from exploding batteries.

This makes them more reliable in case of 1 flawed battery exploding the whole pack.