First, the meaning is different.
radish
Radish; Turnip; kohlrabi
Small carrot
Radish (small)
Second, the usage is different.
radish
Turnip is generally white-skinned, with extremely large roots and relatively large volume.
My nephew likes to eat raw radish.
My nephew likes to eat radishes raw.
Small carrot
Radish, an English word, is mainly used as a noun, which translates as "radish, radish; (radish) name; (Russian) radish; (Cyprus) Radic ".
She carved a flower out of radish.
She carved the radish into a flower.
Third, the emphasis is different.
radish
Turnip: A plant widely cultivated in Eurasia, belonging to Cruciferae, having large fleshy edible roots that turn from yellow to white.
Small carrot
Radishes are generally eaten raw, with a strong Chili flavor, most of which are red and white skins.