The Sun is a star because it produces its own light and heat through nuclear fusion in its core. This is a process where hydrogen atoms fuse together to form helium, releasing immense energy in the form of light and heat.

The Moon, on the other hand, does not produce its own light. It reflects the light of the Sun, making it appear luminous to us.

Here's a breakdown of the key differences:

Sun:

* Star: Yes

* Light source: Produces its own light

* Heat source: Produces its own heat

* Composition: Mostly hydrogen and helium

* Energy source: Nuclear fusion

Moon:

* Star: No

* Light source: Reflects sunlight

* Heat source: No intrinsic heat, gets warm from sunlight

* Composition: Mostly rock and dust

* Energy source: None, relies on external energy from the Sun

In short, the Sun is a giant ball of hot gas that generates its own energy, while the Moon is a rocky body that shines only by reflecting sunlight.