roller coaster vs turbulence

roller coaster and turbulence both are nouns.

Word	Noun	Adjective	Verb	Adverb
roller coaster	Yes	No	No	No
turbulence	Yes	No	No	No

As nouns, turbulence is a hypernym of roller coaster; that is, turbulence is a word with a broader meaning than roller coaster:

roller coaster: anything characterized by abrupt and extreme changes (especially up and down)
turbulence: a state of violent disturbance and disorder (as in politics or social conditions generally)

Other hypernyms of roller coaster include Sturm und Drang, upheaval.

roller coaster (noun)	turbulence (noun)
elevated railway in an amusement park (usually with sharp curves and steep inclines)	unstable flow of a liquid or gas
anything characterized by abrupt and extreme changes (especially up and down)	a state of violent disturbance and disorder (as in politics or social conditions generally)
	instability in the atmosphere