In scientific terms the mass of an object is the amount of matter in the object. It is measured in kilograms and does not vary according to its position. The weight of an object is the force exerted on that object by gravity. The main source of difficulty is that in general when people talk of the 'weight' of an object they expect it to be measured in kilograms, not Newton. It seems that the ideas of weight and mass are confused, so that when the 'weight' of an object is mentioned, it is the amount of matter in it rather than the force attracting it towards the Earth that is foremost in many people's minds. The spring weighing machine works on a different principle. In this case, the force which compresses a spring is measured by the degree of compression.