To begin with, the terms “hypergiant” and “supergiant” are both a bit general. For the most part, these terms are loosely used to refer to the largest and most luminous (brightest and thus most energetic) stars in the universe. The exact term that one should use depends on the specific star that one is discussing (its size and luminosity). There are yellow hypergiants, red supergiants, blue supergiants etc.). You don’t need all the specifications about where all the cutoff points are. —From Quarks to Quasars.