babies'-breath vs baby's breath

babies'-breath and baby's breath both are nouns.

Word	Noun	Adjective	Verb	Adverb
babies'-breath	Yes	No	No	No
baby's breath	Yes	No	No	No

As nouns, babies'-breath and baby's breath are synonyms defined as:

babies'-breath and baby's breath: tall plant with small lance-shaped leaves and numerous tiny white or pink flowers

Other synonyms of babies'-breath include Gypsophila paniculata.

babies'-breath (noun)	baby's breath (noun)
tall plant with small lance-shaped leaves and numerous tiny white or pink flowers	tall plant with small lance-shaped leaves and numerous tiny white or pink flowers