obstruction vs hang-up

obstruction and hang-up both are nouns.

Word	Noun	Adjective	Verb	Adverb
obstruction	Yes	No	No	No
hang-up	Yes	No	No	No

As nouns, hang-up is a hyponym of obstruction; that is, hang-up 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
hang-up: an unforeseen obstacle

Other hyponyms of obstruction include barrier, roadblock, hitch, rub, snag, hurdle, stymie, stymy.

obstruction (noun)	hang-up (noun)
getting in someone's way	an unforeseen obstacle
the act of obstructing	an emotional preoccupation
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