impediment vs obstacle

impediment and obstacle both are nouns.

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

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

impediment: any structure that makes progress difficult
obstacle: an obstruction that stands in the way (and must be removed or surmounted or circumvented)

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

impediment: 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 impediment include albatross, millstone, bind, diriment impediment, drag, obstruction, straitjacket.

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