Explain to me why some cooling towers are 300 feet tall, and others look like a 30 by 30 foot cubicle on top of a building?

"The size of the cooling tower will depend greatly on the type of application the cooling tower is meant for. Facilities such as power plants, steel processing plants, petroleum refineries, or petrochemical plants usually install field erected type cooling towers due to their greater capacity for heat rejection. Field erected towers are usually much larger in size compared to the package type cooling towers."