Single action airbrushes have a trigger or button that controls the flow of paint or other material. When the trigger is pressed, the paint flow is initiated, and the amount of paint that is sprayed is determined by the adjustment of the needle in the nozzle. This type of airbrush is easy to use and is suitable for basic applications where a constant amount of paint is needed.

On the other hand, dual action airbrushes have a trigger that controls both the airflow and the amount of paint that is sprayed. When the trigger is pressed down, air flows through the airbrush, and when it is pulled back, the paint is released. This allows for more control over the amount of paint that is sprayed, making it more suitable for fine detail work and intricate designs.

In summary, the main difference between single action and dual action airbrushes is the level of control over the amount of paint that is sprayed. Single action airbrushes have a fixed flow of paint while dual action airbrushes allow for more precise control over the amount of paint that is sprayed.