preparation vs nebula

preparation and nebula both are nouns.

Word	Noun	Adjective	Verb	Adverb
preparation	Yes	No	No	No
nebula	Yes	No	No	No

As nouns, nebula is a hyponym of preparation; that is, nebula is a word with a more specific, narrower meaning than preparation:

preparation (noun)	nebula (noun)
activity leading to skilled behavior	(pathology) a faint cloudy spot on the cornea
preparatory school work done outside school (especially at home)	an immense cloud of gas (mainly hydrogen) and dust in interstellar space
the activity of putting or setting in order in advance of some act or purpose	cloudiness of the urine
the act of preparing something (as food) by the application of heat	a medicinal liquid preparation intended for use in an atomizer
the cognitive process of thinking about what you will do in the event of something happening
(music) a note that produces a dissonant chord is first heard in a consonant chord
the state of having been made ready or prepared for use or action (especially military action)
a substance prepared according to a formula