luxury vs lavishness

luxury and lavishness both are nouns.

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

As nouns, luxury and lavishness are synonyms defined as:

luxury and lavishness: the quality possessed by something that is excessively expensive

Other synonyms of luxury include sumptuosity, sumptuousness.

luxury (noun)	lavishness (noun)
something that is an indulgence rather than a necessity	the activity of excessive spending
the quality possessed by something that is excessively expensive	the quality possessed by something that is excessively expensive
wealth as evidenced by sumptuous living