ABCs vs character set

ABCs and character set both are nouns.

Word	Noun	Adjective	Verb	Adverb
ABCs	Yes	No	No	No
character set	Yes	No	No	No

As nouns, character set is a hypernym of ABCs; that is, character set is a word with a broader meaning than ABCs:

ABCs: a character set that includes letters and is used to write a language
character set: an ordered list of characters that are used together in writing or printing

Other hypernyms of ABCs include script.

ABCs (noun)	character set (noun)
a character set that includes letters and is used to write a language	an ordered list of characters that are used together in writing or printing