An opera tells its whole story through singing over orchestral music, with little or no spoken dialogue, while a musical mixes songs with spoken scenes. Think of "La Bohème" sung start to finish versus a West End musical where characters talk, then suddenly break into a number.
The core difference
Opera is sung almost throughout, whereas a musical alternates between spoken dialogue and songs.
- opera — a theatrical work told mainly through singing, with orchestral music: Verdi composed some of the most famous operas ever written.
- musical — a stage show or film built around songs and dance numbers performed by the cast: They took the kids to see a West End musical for their birthday.
How to tell them apart
The quickest test is dialogue: if the characters mostly sing their lines, including ordinary conversation, you are watching an opera. If they speak normally and only sing at set musical numbers, it is a musical. Opera also leans on classically trained voices and a full orchestra, while musicals draw on a wider range of pop, jazz and Broadway styles.
The confusion usually comes up when people describe any big, song-heavy production as "an opera" out of habit, or call a sung-through show like Les Misérables a musical, which is fair, since it does keep the format's song-and-scene structure even without much spoken dialogue.
