What are the different types of nebulae?
Bright Diffuse Nebula, Planetary Nebula, and Supernova Remnant
Bright diffuse Nebula are areas of hydrogen gas where new stars are formed.
i.e. Great Orion Nebula
The other two are connected to the dying stage of a star:
Planetary Nebula are the shells of gas that were thrown from red giant stars.
i.e. Cat's Eye Nebula
Supernova Remnant are those leftover from a massive stars' explosion.
i.e. Crab Nebula