a galaxy is a massive, gravitationally bound. system that consists of stars and stellar remnants, an interstellar medium of gas dust, and an important but poorly understood component tentatively dubbed dark matter. typical galaxies range from dwarfs with a few as ten milion of stars. sometimesgalaxies can have other galaxies around them.
a star is a massive, lominous ball of plasma held together by gravit. the nearest star to earth is the sun. which is the sourse of most of the energy on earth. the stars are grouped together into constelations. the star have it's own light.