Supplementary unit is a unit which contains several base units together, for example, involves a unit of velocity is meters/second, which is the base unit is meters and seconds.
Extra units are units which have a base unit connected to multiple units, such as units of speed in meters / second, which is a meter and a second base unit.
Auxiliary unit is a unit which has a base unit, multiple units involved, such as the unit of speed as M / s, which have meters and second is the base unit.