There are about 1.77 pints of confectioner's sugar in a pound, and there is about 1 pint of butter in a pound. Pints are a measure of volume, and pounds are a measure of mass.
Different types of matter have different masses. It can be deduced from the above figures that butter is more dense than confectioner's sugar. Butter carries more mass per unit of volume than confectioner's sugar does. Mass is defined as the weight of an object on the surface of the Earth. A pint of butter weighs more on the Earth than it does on the Moon. The mass of a pint of butter is the same everywhere.