obstruction vs hurdle

obstruction and hurdle both are nouns.

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

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

obstruction: something immaterial that stands in the way and must be circumvented or surmounted
hurdle: an obstacle that you are expected to overcome

Other hyponyms of obstruction include barrier, roadblock, hang-up, hitch, rub, snag, stymie, stymy.

obstruction (noun)	hurdle (noun)
getting in someone's way	the act of jumping over an obstacle
the act of obstructing	a light movable barrier that competitors must leap over in certain races
any structure that makes progress difficult	an obstacle that you are expected to overcome
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

obstruction (verb)	hurdle (verb)
	jump a hurdle