Somebody said they are different because of gravity.
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You’d have the same mass if you’re on earth or on the moon, but the moon is like 1/6 the mass so gravity is 1/6, so you’d weight 1/6 as much as on earth
Mass is a property of matter, while weight is the force that gravity imposes on that matter
Weight is dependent on gravitational force. It’s a measure of that gravitational force, usually on Earth. Mass, which measures the amount of matter in an object, exists whether gravity acts on it or not. The same object has the same mass on Earth, the Moon, or in the middle of space, but has different weights at each of those locations.
However, on Earth weight can be used to measure mass. Since the same gravitational force acts on all objects in the same place on Earth, comparing their weights will reveal their mass. On Earth, mass equals weight divided by the acceleration of gravity.
Mass remains constant despite any gravitational forces. Weight is merely the effects of gravity acting upon matter.
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Think of Mass as how much stuff is contained inside say an object, and weight is how heavy that object is because of gravity. The same object will have the same mass on Mars as it would on Earth. But their weights would be different. In Weaker gravity, objects would weigh less as weight is basically how strong gravity is pulling it towards the floor.
Mass is “how much matter” (how many atoms, to fudge the facts a little) something is made of. Gravity is “how hard is gravity pulling on you”.
Your mass only changes if you diet, work out, cut pieces off yourself, or something like that, but your weight is one number on Earth, a lower number on the Moon or Mars, a higher number on Jupiter, and zero in deep space.
As long as you spend your whole life on the surface of Earth, there isn’t really a practical difference between the two. It becomes important to distinguish between them if you’re talking about objects that are at least partway out of Earth’s gravity field.
Stand on a scale and try to jump but only just a little, so your feet won’t lift the ground. The number on the scale will be smaller for less than a second, your weight on the scale will be smaller. Did your mass change throughout the whole process? No
All stuff has mass. It is a basic part of being stuff. It is what scientists call a constant because no matter where the stuff is, it will always have the same mass.
Gravity is caused by mass. Why this is gets very complicated.
A mass sitting all by itself doesn’t have weight as we mean it. It only has weight when it is affected by being close to another mass. Technically, even a tiny mass creates a really tiny amount of gravity. But for any mass we can move around by hand, the amount of gravity it makes is so teeny tiny that we can ignore it most of the time.
When we weigh something, we are not measuring mass directly. What we are doing is measuring how much local gravity is pulling on that mass.
(It is easy to measure how much the Earth is pulling on a 1 Kg test mass, but extremely difficult to measure the minute amount the test mass is pulling on the Earth.)
This is why a given mass sitting on a scale here on Earth will weigh more than the exact same mass sitting on a scale that is on the Moon. The Moon is smaller, so there is less mass. Less mass means the Moon creates less gravity than the Earth can. So it doesn’t pull on the test mass as strongly. Weight equals mass X gravity.
The reason we can get mass and weight so easily confused is because the amount of gravity the Earth generates is used as a standard reference for all kinds of measurements. Basically, we decided that Earths gravity has a value of 1. So a 1 kilogram mass, multiplied by 1 (Earths gravity) equals 1 Kg of weight. That same mass on the Moon weighs 1 Kg X .166 (the percentage of Earth gravity the Moon can generate) = 16.6 grams.
Because in our daily life, 1 Kg of mass always equals 1 Kg of weight, we never think about what is really going on when we weigh a mass.
Mass is (effectively) constant. It’s a measure of how much “stuff” something is. You can easily measure it against a known quantity of stuff (those teeter totter balancing scales), but there are other ways too. Weight is subjective based on gravity. It’s basically a measure of mass modified by how much gravity is pulling on it.
Just a simple example would be your mass would be the same regardless of if you’re on Earth, the Moon, Mars, or even just floating in space. You’re approximately the same amount of “stuff” (atoms and all) regardless of where you are. Weight obviously would change based on how much gravity could pull on that “stuff”. It’s to the point where in space, far enough away from gravitational bodies, you’d essentially be at 0 weight because nothing is pulling on you but you’re still the same size and all.
In short, mass is just plain stuff. Weight is what happens to mass when being affected by gravity.
It’s kind of like the difference between how much money you have and what you can buy with it. Like if you put $10 in a safe and take it out in 20 years, it’ll still be $10, but the cost of stuff will make it probably buy less stuff than currently does. For an even shorter term example, $10 will buy different amount of gas today than it will tomorrow. It’s still $10, but it’s worth a different amount of goods.
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