Prasad is the edibles and sometimes non edibles offerings to God and Deities. Naivedya is also Prasad but it is only edible offerings. Part of those offerings is returned to the devotee after he/she offers it to God in Temple. If it is in home, people put, wear or eat those offerings as Prasad.
Literally, the edible part of pooja samagri is navedhya and all other offerings are Prasad. After offering everything becomes Prasad. Therefore, to understand what we received from God physically is Prasad and blessings are Ashirbad.
Prasad Food for Nepali Pooja