What is the difference between a planetary nebula and a supernova remnant?

Planetary nebulae and supernova remnants are both fascinating astronomical phenomena, but they are actually quite different.

A planetary nebula is formed from the outer layers of a low-mass star that has reached the end of its life. As the star runs out of fuel, it sheds its outer layers, which are then illuminated by the star's remaining core, creating a beautiful, glowing cloud of gas and dust.

A supernova remnant, on the other hand, is the expanding shell of gas and dust that is left behind after a massive star has exploded. The explosion releases a tremendous amount of energy, which causes the star to completely disintegrate, leaving behind a rapidly expanding cloud of debris.

So, the main difference between a planetary nebula and a supernova remnant is the type of star that created them. Planetary nebulae are created by low-mass stars, while supernova remnants are created by massive stars. Additionally, planetary nebulae are typically smaller and less bright than supernova remnants, and have a more spherical shape.