hair's-breadth vs whisker

hair's-breadth and whisker both are nouns.

Word	Noun	Adjective	Verb	Adverb
hair's-breadth	Yes	No	No	No
whisker	Yes	No	Yes	No

As nouns, hair's-breadth and whisker are synonyms defined as:

Other synonyms of hair's-breadth include hair, hairsbreadth.

hair's-breadth (noun)	whisker (noun)
a very small distance or space	a long stiff hair growing from the snout or brow of most mammals as e.g. a cat
	a very small distance or space

hair's-breadth (verb)	whisker (verb)
	furnish with whiskers