The difference between weight and mass can be a bit confusing. Mass is a description of how much of something there is and is not affected by any force like gravity. Weight on the other hand is a measure of force, such as the force due to gravity. The larger something's mass is, the larger it's weight. Now here's the really confusing part, we generally don't use these terms correctly!

Most of the time, we determine weight using a scale which measures the force of gravity on our body. But we report that as a mass, even though the scale was actually telling us a force, not a mass. The scale tells us a mass because it converts the force into a mass. Kilograms and lbs are usually the units used for weight when in fact those are units of mass.

For the case of a solid that has a mass of 180g on the moon, it would have the same mass on Earth. As long as nothing was taken away from the solid, it's mass can't change. However,the force of gravity is lower on the moon than the Earth because the moon is smaller. So the solid would have a smaller weight on the moon than the Earth, but the same mass.