extravagance vs excessiveness

extravagance and excessiveness both are nouns.

Word	Noun	Adjective	Verb	Adverb
extravagance	Yes	No	No	No
excessiveness	Yes	No	No	No

As nouns, excessiveness is a hypernym of extravagance; that is, excessiveness is a word with a broader meaning than extravagance:

extravagance: the quality of exceeding the appropriate limits of decorum or probability or truth
excessiveness: immoderation as a consequence of going beyond sufficient or permitted limits

Other hypernyms of extravagance include excess, inordinateness.

extravagance (noun)	excessiveness (noun)
the activity of excessive spending	immoderation as a consequence of going beyond sufficient or permitted limits
the trait of spending extravagantly
the quality of exceeding the appropriate limits of decorum or probability or truth