correspondence vs letter

correspondence and letter both are nouns.

Word	Noun	Adjective	Verb	Adverb
correspondence	Yes	No	No	No
letter	Yes	No	Yes	No

correspondence (noun)	letter (noun)
similarity by virtue of corresponding	a written message addressed to a person or organization
compatibility of observations	the conventional characters of the alphabet used to represent speech
(mathematics) an attribute of a shape or relation; exact reflection of form on opposite sides of a dividing line or plane	an award earned by participation in a school sport
communication by the exchange of letters	a strictly literal interpretation (as distinct from the intention)
the relation of corresponding in degree or size or amount	owner who lets another person use something (housing usually) for hire

correspondence (verb)	letter (verb)
	mark letters on or mark with letters
	set down or print with letters
	win an athletic letter