Jupiter is the largest planet in our solar system, but it is significantly smaller than the Sun. In terms of diameter, Jupiter's diameter is about one-tenth that of the Sun. When comparing volumes, you could fit over 1,000 Jupiters inside the Sun. This size difference highlights the distinction between a gas giant planet and a star. Despite its size, Jupiter's mass is still only about 1/1000th the mass of the Sun. The Sun's immense size and mass are what enable the nuclear fusion at its core, a process that doesn't occur in Jupiter.