rotary wing vs airfoil

rotary wing and airfoil both are nouns.

Word	Noun	Adjective	Verb	Adverb
rotary wing	Yes	No	No	No
airfoil	Yes	No	No	No

As nouns, airfoil is a hypernym of rotary wing; that is, airfoil is a word with a broader meaning than rotary wing:

rotary wing: the long airfoil that rotates to provide the lift that supports a helicopter in the air
airfoil: a device that provides reactive force when in motion relative to the surrounding air; can lift or control a plane in flight

Other hypernyms of rotary wing include aerofoil, control surface, surface.

rotary wing (noun)	airfoil (noun)
the long airfoil that rotates to provide the lift that supports a helicopter in the air	a device that provides reactive force when in motion relative to the surrounding air; can lift or control a plane in flight