pomposity vs ostentation

pomposity and ostentation both are nouns.

Word	Noun	Adjective	Verb	Adverb
pomposity	Yes	No	No	No
ostentation	Yes	No	No	No

As nouns, pomposity and ostentation are synonyms defined as:

pomposity and ostentation: lack of elegance as a consequence of being pompous and puffed up with vanity

Other synonyms of pomposity include inflation, ostentatiousness, pompousness, pretentiousness, puffiness, splashiness.

pomposity (noun)	ostentation (noun)
lack of elegance as a consequence of being pompous and puffed up with vanity	pretentious or showy or vulgar display
	lack of elegance as a consequence of being pompous and puffed up with vanity
	a gaudy outward display