The mass of an object is the amount of matter it contains. Also, mass is a fundamental quantity like length and time. It is usually denoted by M.

We know that every object in the surface of the earth is attracted towards the centre of the earth due to gravity. The force due to gravity is called gravitational force. The weight of an object is a measure of the force exerted on the object by gravity, or the force needed to support it.

Weight is denoted by W and is equal to M * g where M is the mass of the object and g is the acceleration due to gravity.

Hence, mass is not weight. But weight is a force due to the action of gravity.

Let us consider an example. Let the mass of the object be 100Kg. Now the weight of the same object on earth will be = M * g = 100 Kg * 9.8 m/s² = 980N which is a kind of force.

Now consider the same object when its weight is measured in moon will be = M * g¹ which is acceleration due to gravity in moon;

Acceleration due gravity in moon = g¹ = g/6 = 9.8/ 6 m/s²

Hence, weight of the object in moon = M * g¹ = 100 * (9.8/ 6) = 162.2N

Thus mass does not change from place to place whereas weight changes from place to place.