ABCs vs alphabet

ABCs and alphabet both are nouns.

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

As nouns, ABCs and alphabet are synonyms defined as:

ABCs and alphabet: a character set that includes letters and is used to write a language

Other synonyms of ABCs include ABC's, ABC.

ABCs (noun)	alphabet (noun)
a character set that includes letters and is used to write a language	the elementary stages of any subject (usually plural)
	a character set that includes letters and is used to write a language