1. Energy Source: Stars produce their own light and heat through nuclear fusion, where they fuse lighter elements like hydrogen into heavier ones like helium. This process releases immense energy. Planets, on the other hand, do not have nuclear fusion occurring within them. They primarily reflect light from their host star.
2. Mass and Size: Stars are much larger and more massive than planets. They are typically composed of hydrogen and helium gas, while planets are primarily made of rock, ice, or gas. The immense gravity of a star is what allows for nuclear fusion to occur.
