Ground is actually from the ramp area to the runway (so basically controls all the taxiways). Tower controls aircraft operating on the runways only. Otherwise that's pretty much correct. In a lot of areas the approach and departure are the same controller, just different name depending on whether the aircraft is arriving or departing.
Approach controls are divided into small sectors laterally and sometimes vertically to divide up the workload
Last edited by Lost; Jan 7, 2018 at 10:07 am