high life vs lavishness

high life and lavishness both are nouns.

Word	Noun	Adjective	Verb	Adverb
high life	Yes	No	No	No
lavishness	Yes	No	No	No

As nouns, high life and lavishness are synonyms defined as:

Other synonyms of high life include extravagance, highlife, prodigality.

high life (noun)	lavishness (noun)
the activity of excessive spending	the activity of excessive spending
	the quality possessed by something that is excessively expensive