flying vs aviation

flying and aviation both are nouns.

Word	Noun	Adjective	Verb	Adverb
flying	Yes	Yes	No	No
aviation	Yes	No	No	No

As nouns, aviation is a hypernym of flying; that is, aviation is a word with a broader meaning than flying:

Other hypernyms of flying include air, air travel.

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

flying (adjective)	aviation (adjective)
hurried and brief
moving swiftly