The term pruning covers a broad spectrum of tree care.
Crown thinning opens up the tree to let more sunlight for better lawns and more light coming into houses.
Crown cleaning removes dead, diseased, crowded and low vigor branches from the trees canopy.
Crown reduction is done to reduce tree height or spread by pruning back leaders to lateral branches. This is not topping. Topping is the indiscriminate cutting of branches to achieve the desired height. If the desired height cannot be attained by Crown reduction, the tree might have to be removed.