Edible Parts of Fruits

An aril is a fleshy outgrowth that arises from the funicle (stalk of the ovule) and covers the seed like an additional coat.
In litchi the white, fleshy, juicy edible part is the aril surrounding the seed.
In custard apple (an etaerio of berries) the edible part is the fleshy pericarp of the individual berries.
In pomegranate (a balausta) the edible part is the juicy testa of the seeds.
In orange (a hesperidium) the edible part is the juicy placental hairs arising from the endocarp.
So the fruit in which the edible part is the aril is litchi.

An aril is a fleshy outgrowth arising from the funicle or the hilum, which covers the seed as an extra coat.
In litchi the white, juicy, sweet edible part surrounding the seed is the aril.
The outer rough, reddish skin is the pericarp and is not eaten.
Other examples: in mango and coconut the edible part is the mesocarp and endosperm respectively, and in pomegranate it is the juicy testa.
So the edible part of litchi is the juicy aril.