millstone vs hindrance

millstone and hindrance both are nouns.

Word	Noun	Adjective	Verb	Adverb
millstone	Yes	No	No	No
hindrance	Yes	No	No	No

As nouns, hindrance is a hypernym of millstone; that is, hindrance is a word with a broader meaning than millstone:

millstone: (figurative) something that hinders or handicaps
hindrance: something immaterial that interferes with or delays action or progress

Other hypernyms of millstone include balk, baulk, check, deterrent, handicap, hinderance, impediment.

millstone (noun)	hindrance (noun)
one of a pair of heavy flat disk-shaped stones that are rotated against one another to grind the grain	the act of hindering or obstructing or impeding
any load that is difficult to carry	any obstruction that impedes or is burdensome
(figurative) something that hinders or handicaps	something immaterial that interferes with or delays action or progress