* Sirius is a binary star system, meaning it has two stars orbiting each other. The brightest star in the system, Sirius A, is a main sequence star (like our sun). It's actually slightly larger and more massive than our sun, but it's still classified as a main sequence star.
* The Sun is the star at the center of our solar system. It's also a main sequence star, but it's much smaller and less massive than Sirius A.
Supergiants are stars in a later stage of their life, much larger and brighter than main sequence stars. While Sirius A may become a supergiant in the distant future, it's not a supergiant now.
