alphabet vs letter

alphabet and letter both are nouns.

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

alphabet (noun)	letter (noun)
the elementary stages of any subject (usually plural)	a written message addressed to a person or organization
a character set that includes letters and is used to write a language	the conventional characters of the alphabet used to represent speech
	an award earned by participation in a school sport
	a strictly literal interpretation (as distinct from the intention)
	owner who lets another person use something (housing usually) for hire

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