The large voltage drop across a load is equal to the source voltage. Which means that current enters a lamp at 120 V and leaves that lamp at 0 V. Sometimes the wires themselves have enough resistance to be part of the load, so some of the voltage is dropped just overcoming that resistance. This is what usually is referred to as voltage drop.
Hipot is an abbreviation for high potential. Traditionally, Hipot is a term given to a class of electrical safety testing instruments used to verify electrical insulation in finished appliances, cables or other wired assemblies, printed circuit boards, electric motors, and transformers.