When you use the terms heavier or lighter to compare different objects with the same volume, what property of the objects are you usually comparing?

When two object occupy the same space or have the same volume, but one of them is heavier than the other. This means that the heavier object is having a higher mass which results in a higher density than the other (lighter) object.

Note that density is calculated using the following rule:
density = mass / volume

C. definite shape, definite volume. that is a solid.