liaison vs affair

liaison and affair both are nouns.

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

As nouns, liaison and affair are synonyms defined as:

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

liaison (noun)	affair (noun)
a channel for communication between groups	a vaguely specified concern
a usually secretive or illicit sexual relationship	a formal or official social gathering or ceremony of people
	a usually secretive or illicit sexual relationship