ostentatiousness vs inelegance

ostentatiousness and inelegance both are nouns.

Word	Noun	Adjective	Verb	Adverb
ostentatiousness	Yes	No	No	No
inelegance	Yes	No	No	No

As nouns, inelegance is a hypernym of ostentatiousness; that is, inelegance is a word with a broader meaning than ostentatiousness:

ostentatiousness: lack of elegance as a consequence of being pompous and puffed up with vanity
inelegance: the quality of lacking refinement and good taste

ostentatiousness (noun)	inelegance (noun)
lack of elegance as a consequence of being pompous and puffed up with vanity	the quality of lacking refinement and good taste