preventive vs obstruction

preventive and obstruction both are nouns.

Word	Noun	Adjective	Verb	Adverb
preventive	Yes	Yes	No	No
obstruction	Yes	No	No	No

As nouns, obstruction is a hypernym of preventive; that is, obstruction is a word with a broader meaning than preventive:

Other hypernyms of preventive include impediment, impedimenta, obstructer, obstructor.

preventive (noun)	obstruction (noun)
remedy that prevents or slows the course of an illness or disease	getting in someone's way
an agent or device intended to prevent conception	the act of obstructing
any obstruction that impedes or is burdensome	any structure that makes progress difficult
	something immaterial that stands in the way and must be circumvented or surmounted
	the physical condition of blocking or filling a passage with an obstruction

preventive (adjective)	obstruction (adjective)
tending to prevent or hinder
preventing or contributing to the prevention of disease