What is mass?
Mass is the amount of matter that an object contains. However, due to the ambiguity associated with the definition of matter, such a definition causes a lot of controversy and criticism. A simpler and more understandable way to define the concept of mass is to represent it in terms of inertia.
The inertia of an object is its property to remain in a state of motion or rest until some external force changes this state.
The greater the mass, the more difficult it is to move or stop the movement of the body.
One of the characteristic features of the mass of an object is that it is constant, regardless of its position in space. According to the law of universal gravitation, two objects are attracted to each other with a force proportional to their masses and inversely proportional to the square of the distance between them. Moreover, the force of gravitational attraction itself does not affect the value of the mass of these objects.
So, for example, a stone weighing 60 kg on Earth will have a mass of 60 kg on Mars, Jupiter or any other corner of our infinite universe. Here we do not 
consider the effects described by the special theory of relativity, when the mass changes when moving at relativistic speeds close to the speed of light. Consideration of these effects is beyond the scope of this article.
What is weight?
The weight of an object indicates how heavy it is. Because of this, weight and mass are often used synonymously. However, technically, weight is the force that a mass-containing object exerts on another body solely under the influence of gravity.
While mass is independent of gravity, weight is the embodiment of that force. Since weight is a force, its unit of measurement is Newton.
The force of gravity acting on a body on the surface of the Earth is equal to the mass of the body multiplied by the acceleration of gravity (this value is 9.8 m / s2).