“Air Force One” is used to designate any Air Force aircraft carrying the President of the US, but it is now standard practice to use the term to refer to specific planes that are equipped to transport the Commander-in-Chief.
Planes carrying the vice president are designated as. When VC-25A or the currently under development VC-25B are in the air but not carrying the president, air traffic controllers may refer to them by their tail numbers, Special Air Missions (SAM) 28000 and 29000, or by a call sign of their choosing.