Pind Daan: This is a general ancestral rite performed for all deceased ancestors (usually annually during Pitru Paksha or upon death) to nourish and appease them, ensuring their peaceful journey. It involves offering rice balls (pindas). It is a fundamental duty for Hindus.
Narayan Bali: This is a specific ritual performed primarily for ancestors who died an unnatural or untimely death, or whose funeral rites were not performed correctly. Its main aim is liberation from the troubled state (Pret Yoni) caused by such deaths and alleviation of resulting Pitru Dosha. While Pind Daan might be part of the Narayan Bali process, Narayan Bali addresses a specific type of death and associated problems.