air space vs airspace

air space and airspace both are nouns.

Word	Noun	Adjective	Verb	Adverb
air space	Yes	No	No	No
airspace	Yes	No	No	No

As nouns, air space and airspace are synonyms defined as:

air space and airspace: the space in the atmosphere immediately above the earth

air space (noun)	airspace (noun)
the space in the atmosphere immediately above the earth	the atmosphere above a nation that is deemed to be under its jurisdiction
	the space in the atmosphere immediately above the earth