niceness vs subtlety

niceness and subtlety both are nouns.

Word	Noun	Adjective	Verb	Adverb
niceness	Yes	No	No	No
subtlety	Yes	No	No	No

As nouns, niceness and subtlety are synonyms defined as:

niceness and subtlety: the quality of being difficult to detect or analyze

niceness (noun)	subtlety (noun)
the quality of nice	the quality of being difficult to detect or analyze
the quality of being difficult to detect or analyze	a subtle difference in meaning or opinion or attitude
a courteous manner that respects accepted social usage