banister vs barrier

banister and barrier both are nouns.

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

As nouns, barrier is a hypernym of banister; that is, barrier is a word with a broader meaning than banister:

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

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