yus vs alphabetic character

yus and alphabetic character both are nouns.

Word	Noun	Adjective	Verb	Adverb
yus	Yes	No	No	No
alphabetic character	Yes	No	No	No

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

yus: a Common Slavonic nasal vowel in the early Cyrillic and Glagolitic alphabets.
alphabetic character: the conventional characters of the alphabet used to represent speech

Other hypernyms of yus include letter, letter of the alphabet.

yus (noun)	alphabetic character (noun)
a Common Slavonic nasal vowel in the early Cyrillic and Glagolitic alphabets.	the conventional characters of the alphabet used to represent speech