capriccio vs opus

capriccio and opus both are nouns.

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

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

capriccio: an instrumental composition that doesn't adhere to rules for any specific musical form and is played with improvisation
opus: a musical work that has been created

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

capriccio (noun)	opus (noun)
an instrumental composition that doesn't adhere to rules for any specific musical form and is played with improvisation	a musical work that has been created