air travel vs aviation

air travel and aviation both are nouns.

Word	Noun	Adjective	Verb	Adverb
air travel	Yes	No	No	No
aviation	Yes	No	No	No

As nouns, air travel and aviation are synonyms defined as:

Other synonyms of air travel include air.

air travel (noun)	aviation (noun)
travel via aircraft	travel via aircraft
	the art of operating aircraft
	the aggregation of a country's military aircraft
	the operation of aircraft to provide transportation