indecorum vs familiarity

indecorum and familiarity both are nouns.

Word	Noun	Adjective	Verb	Adverb
indecorum	Yes	No	No	No
familiarity	Yes	No	No	No

As nouns, indecorum and familiarity are synonyms defined as:

Other synonyms of indecorum include impropriety, liberty.

indecorum (noun)	familiarity (noun)
an act of undue intimacy	an act of undue intimacy
a lack of decorum	usualness by virtue of being familiar or well known
	close or warm friendship
	a casual manner
	personal knowledge or information about someone or something