Not all galaxies are spiral in shape[1][2], some nebulae are huge[3] and nebula are the nursery of stars[4]. How to tell them apart?

Note

I have already compare both contents, they are very similar both have stars, planets and dusts.

Not all galaxies are spiral in shape[1][2], some nebulae are huge[3] and nebula are the nursery of stars[4]. How to tell them apart?

Note

I have already compare the contents for galaxy and a nebula, they are very similar as both have stars, planets and dusts.