si vs solfa syllable

si and solfa syllable both are nouns.

Word	Noun	Adjective	Verb	Adverb
si	Yes	No	No	No
solfa syllable	Yes	No	No	No

As nouns, solfa syllable is a hypernym of si; that is, solfa syllable is a word with a broader meaning than si:

si: the syllable naming the seventh (subtonic) note of any musical scale in solmization
solfa syllable: one of the names for notes of a musical scale in solmization

si (noun)	solfa syllable (noun)
the syllable naming the seventh (subtonic) note of any musical scale in solmization	one of the names for notes of a musical scale in solmization