The choice between a fog machine and a smoke machine depends on the desired effect and purpose. A fog machine typically produces a dense, low-lying fog that enhances visual appeal and creates an eerie ambiance, commonly used in theatrical performances and haunted houses. On the other hand, a smoke machine generates a lighter, more dispersed smoke suitable for enhancing lighting effects and creating a hazy atmosphere, commonly used in concerts and events. Ultimately, the decision comes down to the specific application and the desired aesthetic outcome.