A supergiant simply is a large giant - so, it is larger (in diameter) than a "regular" giant star.
The primary difference between a giant and a supergiant star lies in their size and luminosity. Giants are typically larger than main-sequence stars but smaller than supergiants, with diameters ranging from about 10 to 100 times that of the Sun. Supergiants, on the other hand, are among the largest stars in the universe, often exceeding 100 times the Sun's diameter and exhibiting significantly higher luminosity. In essence, supergiants represent a more advanced evolutionary stage and are much more massive than giants.
Typically,giant stars have radii between 10 and 100 solar radii and luminosities between 10 and 1,000 times that of the Sun.Whereas Supergiants have a radii between 30 and 1,000 solar radii and luminosities between 30,000 and 100,000 times that of the Sun
one is big one is small
Red giants. By the way, what if it was a white star.
The stars that are like supergiants are called "red giants" or "red supergiants".
one is big one is small
No, a supergiant star is generally larger than a giant star. In the classification of stars, giants are typically larger than main sequence stars but smaller than supergiants. Supergiants represent one of the most massive and luminous stages of stellar evolution, surpassing giants in both size and brightness.
The difference is that the giant star has it's death more seriously but,The huge star is mostly not well important to the huge star.
The mass of the star.
Not exactly. Red giants become white dwarf stars. It is the red supergiants that can become supernovas.
White dwarf Main sequence star (like our sun) Red giant Supergiant
It is the mass of the main sequence star. "High mass" stars can become supergiants (not always red). If you go into more details, you will find this answer is a simplification, but it's OK for most purposes.