Ventilation fans and exhaust fans are both used to move air in and out of a space, but they serve different purposes. Ventilation fans are used to bring fresh air into a space, while exhaust fans are used to remove stale air and odors. Ventilation fans are typically installed in the ceiling or wall and are designed to move air from the outside into the space. Exhaust fans, on the other hand, are typically installed in the wall or ceiling and are designed to move air from the inside of the space to the outside. Both types of fans are important for maintaining a healthy indoor air quality.