toccata vs opus

toccata and opus both are nouns.

Word	Noun	Adjective	Verb	Adverb
toccata	Yes	No	No	No
opus	Yes	No	No	No

As nouns, opus is a hypernym of toccata; that is, opus is a word with a broader meaning than toccata:

toccata: a baroque musical composition (usually for a keyboard instrument) with full chords and rapid elaborate runs in a rhythmically free style
opus: a musical work that has been created

Other hypernyms of toccata include composition, musical composition, piece, piece of music.

toccata (noun)	opus (noun)
a baroque musical composition (usually for a keyboard instrument) with full chords and rapid elaborate runs in a rhythmically free style	a musical work that has been created