finger alphabet vs ABC

finger alphabet and ABC both are nouns.

Word	Noun	Adjective	Verb	Adverb
finger alphabet	Yes	No	No	No
ABC	Yes	No	No	No

As nouns, ABC is a hypernym of finger alphabet; that is, ABC is a word with a broader meaning than finger alphabet:

finger alphabet: an alphabet used by the deaf; letters are represented by finger positions
ABC: a character set that includes letters and is used to write a language

Other hypernyms of finger alphabet include ABC's, ABCs, alphabet.

finger alphabet (noun)	ABC (noun)
an alphabet used by the deaf; letters are represented by finger positions	a character set that includes letters and is used to write a language