barrier vs banister

barrier and banister both are nouns.

Word	Noun	Adjective	Verb	Adverb
barrier	Yes	No	No	No
banister	Yes	No	No	No

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

barrier: a structure or object that impedes free movement
banister: a railing at the side of a staircase or balcony to prevent people from falling

barrier (noun)	banister (noun)
a structure or object that impedes free movement	a railing at the side of a staircase or balcony to prevent people from falling
any condition that makes it difficult to make progress or to achieve an objective
anything serving to maintain separation by obstructing vision or access