Fans utilize power from a motor to generate a volumetric flow of air at a given pressure, and are considered low-pressure air pumps more often than not. A propeller converts torque (turning force) from the motor (typically permanent split capacitor AC induction motors or brushless DC) to increase static pressure across the fan rotor and to increase the kinetic energy of the air particles.

Fans are classified into propeller, tube axial and vane axial styles, and each type has different characteristics. Propeller fans consist of only a motor and propeller and therefore are the simplest. Tube axial are similar to propellers but has a venturi around the propeller to reduce the vortices. Vane axial fans are equipped with vanes that trail behind the propeller in the airflow to straighten the swirling flow.

The flow and pressure properties are the main differences between a fan and a blower. While fans deliver air in an overall direction that is parallel to the fan blade axis, blowers deliver air in a direction that is perpendicular to the blower axis. Hence, fans can be configured to deliver a high flow rate, working against low pressure while blowers to deliver a relatively low flow rate against high pressure. Centrifugal blowers can be squirrel cage type, have a forward curved wheel or a backward curved wheel.

Another major difference is in the mechanism regarding restriction to the air-flow. In a blower, it has an opposite effect on the same motor driving a fan blade. For instance, the load on the motor decreases when the motor is driving a squirrel cage blower. As the system becomes clogged, the blower speeds up. On the other hand, the load on the motor increases and the fan slows down as the airflow system becomes clogged with fan blades.