Pind Daan: A general rite for all departed ancestors, usually performed annually (especially during Pitru Paksha) or after death, to nourish and satisfy them. It’s a fundamental duty.
Narayan Bali: A specific ritual targeted towards souls who died unnaturally or whose final rites were improper. Its primary focus is liberation from a troubled state (Pret Yoni) and resolving the specific Pitru Dosha caused by such deaths. While Pind Daan is often part of Narayan Bali, the latter addresses a very specific type of death and its consequences.