The most important thing to consider when selecting a fruit tree is how big you ultimately want it to be - its mature height. The mature height is affected by many factors but the main one is the rootstock on which the tree has been propagated. A typical apple tree, growing in the wild on its own "seedling" roots, might reach a height of 15ft-25ft. A wild cherry tree will be even larger. By propagating the desired variety onto size-controlling rootstocks, the final height can be limited to something more predicatable and more suitable for a garden or small orchard.
Rootstocks are usually derived from related species of trees which are naturally smaller - or more "dwarfing". Apple trees are usually grafted on to rootstocks derived from related Malus species. For more information about rootstocks see this page.
The rootstock also has a big influence on the time it takes the fruit tree to reach its mature height. In general, the more dwarfing the rootstock the quicker the tree will mature. Apples on the dwarfing M9 or G16 rootstocks may reach their mature height and spread within 4-5 years - which of course means you will be enjoying full crops relatively quickly. Apple trees grown on the MM106 rootstock will take longer (and be bigger of course) - perhaps 5-8 years, but will start bearing a useful crop after 4 years or so. Rates are different for different species, plums for example generally take a couple of years longer than apples to reach maturity.
The next most important factor which will determine the mature size of the tree is the natural vigour of the fruit variety. For example, Bramley's Seedling is a vigorous variety, and grown in the same conditions and on the same rootstock as, say, a Rubinette, is likely to produce a larger tree.
Other factors influencing the mature size of the tree are the local conditions that you provide after planting - soil, climate, annual temperatures, and cultivation techniques. Different varieties have different preferences, and one variety may thrive whilst another struggles in your particular conditions.
We provide approximate mature heights as a guide, but please bear in mind all the above information when deciding what size meets your requirements. If you need advice please use our inquiry form and we will be happy to help.