Hard Fruit doesn’t necessarily refer to fruit that is hard as opposed to soft — all fruit is soft, compared to a rock.
Rather, it refers to fruit that has a relatively long shelf life, and ships a bit more easily, as opposed to soft fruit, such as strawberries or raspberries, which are extremely fragile and have a very short shelf life.
In the Hard Fruit category are fruits such as apples, apricots, bananas, grapefruit, grapes, kiwi, lemons, limes, mandarin oranges, oranges, peaches, pears, plums, quince, tangerines, etc.