flawlessness vs ne plus ultra

flawlessness and ne plus ultra both are nouns.

Word	Noun	Adjective	Verb	Adverb
flawlessness	Yes	No	No	No
ne plus ultra	Yes	No	No	No

As nouns, flawlessness and ne plus ultra are synonyms defined as:

flawlessness and ne plus ultra: the state of being without a flaw or defect

Other synonyms of flawlessness include perfection.

flawlessness (noun)	ne plus ultra (noun)
the state of being without a flaw or defect	the state of being without a flaw or defect