hair's-breadth vs hair

hair's-breadth and hair both are nouns.

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

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

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

hair's-breadth (noun)	hair (noun)
a very small distance or space	a filamentous projection or process on an organism
	cloth woven from horsehair or camelhair; used for upholstery or stiffening in garments
	a covering for the body (or parts of it) consisting of a dense growth of threadlike structures (as on the human head); helps to prevent heat loss
	any of the cylindrical filaments characteristically growing from the epidermis of a mammal
	filamentous hairlike growth on a plant
	a very small distance or space