No, no star is a planet!

A star produces light by nuclear reactions in its interior such as two hydrogen atoms slamming together to produce one helium atom plus lots of heat and light.

Planets on the other hand shine only because they reflect light from their nearby star back out into space.

Stars are not planets. Stars are things like the sun (the sun itself is a star).

Stars and planets are actually different things.

Stars are made primarily out of gas and are extremely hot. They are also much larger than planets.

Planets can be solid, liquid, gas or a combination (earth is primarily a combination of liquid and solid, Jupiter is primarily gas). They are smaller than stars and much less hot.

The answer to your question is mostly about the names that scientists decided to give things.

We say a big object in outer space is a star if it is shining light from nuclear fusion. This is a really crazy thing to do--it's a nuclear reaction, not an ordinary chemical reaction. It takes hydrogen as fuel, puts it under really high pressure at a really high temperature, and turns it into a different element, helium. This gives the star so much energy that it releases a lot of it by radiating light in all directions.

We say a big object in outer space is a planet if it is not doing nuclear fusion, and it is orbiting a star. Planets do not shine light, they just reflect light that comes from stars. If you could turn off the light from the stars, it would be dark and we wouldn't be able to see the planets anymore.

So stars and planets are always separate things. Why didn't we decide to say "stars are planets, too"? I don't know for sure, but I guess it is because stars and planets behave so differently.