The Deployer use items in much the same way a player does.
A Deployer has nine slots in its inventory (You can feed it with tubes).
Upon receiving a redstone pulse, it examines its contents in order(left-to-right, top-to-bottom), and when it finds a non-empty slot, it emulates a player's right click action when holding this item. It can place blocks, fill buckets, till dirt, make fire, shear and do almost everything else that a player can do; except for breaking blocks, which is what a Block Breaker does.
Use cases[]
It is possible to use the Deployer, a Transposer, some Pneumatic Tubes, a Timer, and some kind of storage block to make an automated Wool farm.