Our Sun is a star, a fairly ordinary, medium-sized star. Like all stars, it is a ball of glowing gas, a huge nuclear furnace throwing out enormous quantities of light, heat and other forms of energy. Compared to our Sun, the other stars look tiny, but that is because they are a very long way off. Some stars are more than one hundred times bigger than the Sun.
Astronomers locate stars by reference to the constellations.
A constellation is a group of stars that we can see in one particular part of the night sky. They are not necessarily close together in space. On a much larger scale stars group together into great star islands in space called galaxies. Our Sun and its planets are part of our Galaxy, the Milky Way. The Milky Way is far from being the largest galaxy, yet its size is so vast that it is hard to grasp.