airspace vs air space

airspace and air space both are nouns.

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

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

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

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