perianth vs falls

perianth and falls both are nouns.

Word	Noun	Adjective	Verb	Adverb
perianth	Yes	No	No	No
falls	Yes	No	No	No

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

perianth: collective term for the outer parts of a flower consisting of the calyx and corolla and enclosing the stamens and pistils
falls: the petals or sepals of a flower that bend downward (especially the outer perianth of an iris)

perianth (noun)	falls (noun)
collective term for the outer parts of a flower consisting of the calyx and corolla and enclosing the stamens and pistils	a steep descent of the water of a river
	the petals or sepals of a flower that bend downward (especially the outer perianth of an iris)