In order to contain their rate of growth, fruit trees are grown on a range of rootstocks.  Please click on the following “rootstocks explained” link to view a diagram showing the potential height of mature trees grown on a variety of rootstocks:

Rootstocks explained

To illustrate the effect of rootstock, the following image shows the difference between two untrained cherries of the same age. The tree on the left is grown on Gisela 5 root stock, while the tree on the right is grown on the more vigorous Colt rootstock: