There are trillions of stars throughout the universe and each and every one of them has a different set of physical characteristics. These characteristics include things like color, composition, size, temperature, density, shape and mass.
for example, some of the physical characteristics of the star Altair include:
Mass: 1.7 M☉
Effective temperature :7550K
Size: 1.83 R☉
and the physical characteristics of our sun include:
Mass: 1.0 M☉
Effective temperature: 5800k
Size: 1.0 R☉
When we compare the measurements of these two stars we can see that the Altair is about 1.7 times more massive then our sun, 1.83 times larger, and about 1.3 times hotter at its surface.
While it might be true that stars all have different physical characteristics, these characteristics are limited to only certain colors, sizes, mass’s, shapes, densities and temperatures. When we compared the sun to Altair, the size, mass and temperature of Altair were all greater than the mass, temperature and size of the sun. The reason being, is that these physical characteristics are all related to one another and, the overall structure of the star. For example, there is a direct link between the luminosity of a star (the amount of energy it emits) and its mass. There is also a direct link between the apparent color of a star and its temperature, this is shown using something called the black-body spectrum.
What is a a black body?
A blackbody refers to an opaque object that emits thermal radiation. A perfect blackbody is one that absorbs all incoming light and does not reflect any.
The theoretically perfect black body absorbs all forms of electromanetic radiation. Stars are also blackbody radiators and most of the light directed out of stars is absorbed. This is why different stars have different colors.
As you can see there are three values on the graph above: intensity, temperature and wavelength. When the temperature of a blackbody radiator increases, the overall radiated energy increases and the peak of the radiation curve moves to shorter wavelengths.
http://hyperphysics.phy-astr.gsu.edu/hbase/wien.html
source: https://osr.org/blog/astronomy/altair/