affaire vs liaison

affaire and liaison both are nouns.

Word	Noun	Adjective	Verb	Adverb
affaire	Yes	No	No	No
liaison	Yes	No	No	No

As nouns, affaire and liaison are synonyms defined as:

Other synonyms of affaire include affair, amour, intimacy, involvement.

affaire (noun)	liaison (noun)
a usually secretive or illicit sexual relationship	a channel for communication between groups
	a usually secretive or illicit sexual relationship