Bush Formation and Pruning
The bush is pruned so that the plant directs energy to the fruits, not to additional parts. This also improves air circulation and allows more light to reach the plant.
Tomato Types
Determinate ('bush') grows only to a certain height, is more compact. Flower clusters form approximately every second leaf node.
Indeterminate ('tall', 'vining') grows to an indefinite height, limited only by supports and the length of the season. It forms suckers that, if not pinched, grow indefinitely and can weaken the main plant.
Source: pomidorai.eu