bagatelle vs opus

bagatelle and opus both are nouns.

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

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

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

bagatelle (noun)	opus (noun)
a table game in which short cues are used to knock balls into holes that are guarded by wooden pegs; penalties are incurred if the pegs are knocked over	a musical work that has been created
something of little value or significance
a light piece of music for piano