Most cranes can move a load in a straight line on three independent axes and can be said to have three degrees of freedom.
The main differences between a hoist and a crane are the ways each can move, the ability to convert them to other tasks, and the complexity of their design. A hoist and a crane are used to move objects. While a hoist can only lift or lower them vertically, a crane can also move objects horizontally. Some very advanced crane designs also allow the load to rotate in three dimensions. Generally, the part of a crane that is used to raise and lower a load is a hoist.
A hoist and crane can be used to move a load, but a hoist can only move a load in one direction along a straight vertical line. Such a device is said to have one degree of freedom. A good way to visualize this is to think of an elevator. It moves up and down on an axis, also known as a lifting form, suspended by cables from a lifting mechanism that drives its movement. The elevator is limited to going up and down directly inside this shaft.
Typical cranes can move their loads up and down in a straight line vertically, but they can also move them horizontally back and forth and side to side. Most cranes can move a load in a straight line on three independent axes and can be said to have three degrees of freedom. There are some jobs that a crane and hoist are suitable for. Some tasks, however, require the use of a crane for more flexibility in how and where to move the load.
A common example of this flexibility of movement is the small crane within a claw machine game used to retrieve toys as prizes. The operator positions a crane by moving it forward and backward, as well as left and right, and presses a button to release a claw. An open claw drops vertically into a pile of toys, closes, and retracts upward with or without a toy in hand. There would be little point in this game without the crane feature. With just one lift, the operator could only lower and raise the grapple in the same place each time, requiring no skill.
Specialized cranes called jib cranes often have this same capability, but also incorporate swivel motion for increased performance. They can rotate in up to three independent axes, as well as move in a straight line in those three directions. These rotations are known as roll, pitch, and yaw. This allows a jib crane to operate with up to six degrees of freedom, although some models are designed with fewer degrees of freedom. Jib cranes can be used in robotic applications, for example, or in industrial transportation applications such as trucks, locomotives, or ships.
Another difference between a hoist and a crane is that many cranes can be converted for operations other than moving a load. In demolition, for example, a wrecking ball can be added in order to bring down an unwanted structure. For construction purposes, a shovel can be used to scoop up any dirt or debris that will be moved. Hoists are generally not designed to be converted to uses other than lifting and lowering a load.
Hoists are commonly installed as subcomponents of cranes. They are usually the mechanisms used to raise and lower loads moved by cranes. This is another way a tow truck and a tow truck differ. Cranes are more complex devices than hoists and are not subcomponents of hoists.