Fruit trees cover a wide range of different types of fruit, eg. apple, pear, cherry, peach, and citrus trees. This variety means they can be grown over a range of different climates - e.g. apple is popular in the UK; peach is popular in Texas; and citrus trees are popular in frost-free areas (e.g. Florida and the Mediterranean).
Fruit trees tend to be of a moderate size and have a lot of blossom, so they can be grown for ornamental purposes ("flowering" non-fruiting varieties are common); however, they are usually grown for their fruit. Hence they often need special care as regards pruning and thinning in order to maximize the quantity and size of the fruit.