subtlety vs niceness

subtlety and niceness both are nouns.

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

As nouns, subtlety and niceness are synonyms defined as:

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

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