deterrent vs obstacle

deterrent and obstacle both are nouns.

Word	Noun	Adjective	Verb	Adverb
deterrent	Yes	Yes	No	No
obstacle	Yes	No	No	No

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

deterrent: something immaterial that interferes with or delays action or progress
obstacle: something immaterial that stands in the way and must be circumvented or surmounted

Other hyponyms of deterrent include albatross, millstone, bind, diriment impediment, drag, obstruction, straitjacket.

deterrent (noun)	obstacle (noun)
something immaterial that interferes with or delays action or progress	an obstruction that stands in the way (and must be removed or surmounted or circumvented)
	something immaterial that stands in the way and must be circumvented or surmounted

deterrent (adjective)	obstacle (adjective)
tending to deter