expensiveness vs luxury

expensiveness and luxury both are nouns.

Word	Noun	Adjective	Verb	Adverb
expensiveness	Yes	No	No	No
luxury	Yes	No	No	No

As nouns, luxury is a hyponym of expensiveness; that is, luxury is a word with a more specific, narrower meaning than expensiveness:

Other hyponyms of expensiveness include costliness, dearness, preciousness, lavishness, sumptuosity, sumptuousness.

expensiveness (noun)	luxury (noun)
the quality of being high-priced	something that is an indulgence rather than a necessity
	the quality possessed by something that is excessively expensive
	wealth as evidenced by sumptuous living