nonstop flight vs nonstop

nonstop flight and nonstop both are nouns.

Word	Noun	Adjective	Verb	Adverb
nonstop flight	Yes	No	No	No
nonstop	Yes	Yes	No	Yes

As nouns, nonstop flight and nonstop are synonyms defined as:

nonstop flight and nonstop: a flight made without intermediate stops between source and destination

nonstop flight (noun)	nonstop (noun)
a flight made without intermediate stops between source and destination	a flight made without intermediate stops between source and destination

nonstop flight (adjective)	nonstop (adjective)
	at all times
	(of a journey especially a flight) occurring without stops

nonstop flight (adverb)	nonstop (adverb)
	without stopping