Answer:
All objects can have the same size but have a different mass!
This is true, although it sounds fake. This is one example, there is a Neutron star, and Neutron stars are as big as a city, but they have a mass which is hundreds of times greater than our sun's mass. Because of them having so much mass, they are also having so much gravitational energy, which makes them also have gravity. They're so small, but have so much mass that they can do much. Even a drop of a neutron star can punch open the earth! It's true, so yes, it is possible for objects the SAME size to be having different masses according to that example.
But let's look on how they can have different mass.
They can have different masses becase of different densities. Put a iron ball inside water, and put an apple as close to the iron ball's side, what happens? The apple floats, becuase the apple's mass is less than the water, and the iron ball's mass is MORE than the water. So, because the iron ball is denser than the apple, that's why, it has more mass than the apple. The apple isn't much dense, it isn't as dense as water or the iron ball. But the iron ball is much more denser than the water. So because of the different material densities of the material, that's why it can have different masses.
Remember to Remember those 2 examples I gave you... (neutron star vs sun, iron ball vs apple on water)
