UNDERSTANDING MASS & WEIGHT AND DIFFRENCE BETWEEN THEM:

                        MASS

The mass of an object is a fundamental property of the object; a numerical measure of its inertia; a fundamental measure of the amount of matter in the object. Definitions of mass often seem circular because it is such a fundamental quantity that it is hard to define in terms of something else. All mechanical quantities can be defined in terms of mass, length, and time. The usual symbol for mass is m and its SI unit is the kilogram.

                        WEIGHT

The weight of an object is defined as the force of gravity on the object and may be calculated as the mass times the acceleration of gravity, w = mg. Since the weight is a force, its SI unit is the newton.

DIFFRENCE 

Mass:

1.Mass is the amount of matter contained in a body.

2.Mass of the body is the constant quantity and does not change with the change of position or location.

3.It's SI unit is kilogram.

4.It is a scalar quantity and cantains only magnitude. 

Weight:

1.Weight is the force by which the earth attracts a body toward its centre, Or we can say it is the force on the object which is offered by the gravity.

2.Weight of the body is the variable quantity and changes with the change in position and location due to the acceleration of the gravity acting on it.

3.It's SI unit is newton.

4.It is vector quantity and contains both magnitude as well as direction also.