air cushion vs inflatable cushion

air cushion and inflatable cushion both are nouns.

Word	Noun	Adjective	Verb	Adverb
air cushion	Yes	No	No	No
inflatable cushion	Yes	No	No	No

As nouns, air cushion and inflatable cushion are synonyms defined as:

air cushion and inflatable cushion: a cushion usually made of rubber or plastic that can be inflated

air cushion (noun)	inflatable cushion (noun)
a cushion usually made of rubber or plastic that can be inflated	a cushion usually made of rubber or plastic that can be inflated
a mechanical device using confined air to absorb the shock of motion
the trapped air that supports a hovercraft a short distance above the water or ground