You're giving me too much credit, I meant the guys in the air traffic control tower - I just thought they wore the same giant ear muffs that the guys down on the tarmac wear.
The guys in the tower are ATC, they do ground control (still ATC) and local control, surface to 2500' with a 5-mile radius. The dark room guys (TRACON) do surface to the top of their airspace (depends, 18k, 23k) with a 60-mile radius (roughly). Then there is center/en route, which does air traffic above the TRACON when you are level flying at 30k+.
Simplified version.
Source: Was an air traffic controller.