obstacle vs barrier

obstacle and barrier both are nouns.

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

As nouns, barrier is a hyponym of obstacle; that is, barrier 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
barrier: any condition that makes it difficult to make progress or to achieve an objective

Other hyponyms of obstacle include roadblock, hang-up, hitch, rub, snag, hurdle, stymie, stymy.

obstacle (noun)	barrier (noun)
an obstruction that stands in the way (and must be removed or surmounted or circumvented)	a structure or object that impedes free movement
something immaterial that stands in the way and must be circumvented or surmounted	any condition that makes it difficult to make progress or to achieve an objective
	anything serving to maintain separation by obstructing vision or access