obstacle vs hurdle

obstacle and hurdle both are nouns.

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

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

obstacle: 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 obstacle include barrier, roadblock, hang-up, hitch, rub, snag, stymie, stymy.

obstacle (noun)	hurdle (noun)
an obstruction that stands in the way (and must be removed or surmounted or circumvented)	the act of jumping over an obstacle
something immaterial that stands in the way and must be circumvented or surmounted	a light movable barrier that competitors must leap over in certain races
	an obstacle that you are expected to overcome

obstacle (verb)	hurdle (verb)
	jump a hurdle