obstacle vs baulk

obstacle and baulk both are nouns.

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

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

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

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

obstacle (noun)	baulk (noun)
an obstruction that stands in the way (and must be removed or surmounted or circumvented)	one of several parallel sloping beams that support a roof
something immaterial that stands in the way and must be circumvented or surmounted	something immaterial that interferes with or delays action or progress
	the area on a billiard table behind the balkline

obstacle (verb)	baulk (verb)
	refuse to comply