obstacle vs impediment

obstacle and impediment both are nouns.

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

As nouns, impediment is a hypernym of obstacle; that is, impediment is a word with a broader meaning than obstacle:

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

Other hypernyms of obstacle include impedimenta, obstructer, obstruction, obstructor.

As nouns, impediment is a hypernym of obstacle; that is, impediment is a word with a broader meaning than obstacle:

obstacle: something immaterial that stands in the way and must be circumvented or surmounted
impediment: something immaterial that interferes with or delays action or progress

Other hypernyms of obstacle include balk, baulk, check, deterrent, handicap, hinderance, hindrance.

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