First of all, it helps to clarify what you mean by "size": the diameter? The surface area? The volume? The mass?
Our Sun has a diameter of 1.4 million km.; about 109 times the diameter of Earth. Its area and volume are 109 squared and 109 cubed, respectively (compared to Earth). The Sun's mass is about 330,000 times the mass of Earth.
Stars can be classified into different sizes based on their mass and luminosity. The most common sizes are dwarf stars (like our Sun), giant stars (larger and more luminous than the Sun), and supergiant stars (the largest and most luminous stars, like Betelgeuse and Rigel). There are also intermediate sizes like subgiant stars.
Our own galaxy, the Milky Way consists of about 200 billion stars.
No. Stars vary greatly in size and brightness.
like people, no 2 stars are absolutely identical so yes
Because they cannot visit stars and measure their sizes with a tape measure!
Stars are classified by their color, temperatures, sizes, and brightness, it could also be by composition and radiation.Scientists classify stars by color, luminosity, and temperature.
Most stars are smaller than the Sun, but those that are larger can be a lot larger.
It varies. Stars can be all different sizes!
Hydrogen
They are all three. That is why some stars are called White Dwarfs (they are relatively small) and Red Giants or even Supergiants. The Sun is a middle-sized star.
Most stars in the universe are similar in size to our Sun, which has a radius of about 432,168.6 miles (696,342 kilometers). These stars are classified as main-sequence stars and fall within a range of sizes referred to as G-type stars. However, there is a wide variety of sizes among stars, from tiny red dwarfs to massive supergiants.
Neutral binary stars can have their sizes measured directly by photometry. By observing how the brightness of the system changes over time, astronomers can infer the sizes of the individual stars and the distance between them. This method can provide valuable information about the physical parameters of the binary system.