Air Walkers are used in big cities to help deliver skyscraper type routes. Part Time job in the morning, they meet the Package Driver at the delivery dock. I don't know if they are used to make Pick Ups in the afternoon.
From what I've heard it's the same thing, driver drops off the trailer or a load and somebody, or in some cases, multiple somebodies go through the building delivering it. That way you don't have a vehicle at a loading dock or trying to stop in a busy metro area.
My understanding is that we have two UPSers covering just the Empire State Building. Somebody from NYC, Chicago, or a similar city would be able to speak to it better than I.
Not sure what the job title is though.