alphabet vs ABC's

alphabet and ABC's both are nouns.

Word	Noun	Adjective	Verb	Adverb
alphabet	Yes	No	No	No
ABC's	Yes	No	No	No

As nouns, alphabet and ABC's are synonyms defined as:

alphabet and ABC's: a character set that includes letters and is used to write a language

Other synonyms of alphabet include ABC, ABCs.

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