Some fruit trees DO lose their leaves...but not all.
Deciduous fruit trees lose their leaves. A deciduous tree is one that loses its leaves at the end of the growing season, goes dormant for the winter, and regrows new leaves in the spring. Examples of deciduous fruit trees are the apple, apricot, fig, peach, pear, and plum.
Citrus trees such as orange and grapefruit trees are evergreen. Evergreens are trees that keep their foliage for more than one growing season.
Bananas and pineapples are actually products of herbaceous plants rather trees.