Heading involves cutting back the leader and the branch tips by removing one-third of the previous year’s growth each year. This technique produces bushier young trees, but delays fruit production. It is better suited to species that bear fruit on the current year’s new shoots (peaches, grape vines).
Thinning involves cutting all undesirable branches back fully (to another branch or the trunk). This technique is a good way to discourage suckers and encourage early fruiting. Thinning is appropriate for species that bear fruit on short limbs on mature branches (apples, cherries, plums and pears).