How would you differentiate an opera from a musical?

Answer 1

In the strictest the differences end up in how much is sung .... in Opera every thing is sung accompanied by an orchestra of varying sizes ... so as in the original version of Carmen the recitatives (the plot moving dialog sung parts) were originally spoken (opera comique) and the music was added later so it could be done at the bigger more prestigious opera houses and be an opera in its true sense
the musical developed out of a closely related styles the Singspiel, Operetta, Opera Comique and Semi Opera where some spoken parts were incorporated most likely the term "musical" was developed to make the distinction that much less is being sung than in the operetta forms

all these forms of theatrical experiences incorporate (not every work) all that is available to a theater ....dance scenery actual acting (though some opera singers are lacking there)
there are operas that have full blown ballets in the middle of them (Aida, Faust) and one has a volcano blowing (one of Meyerbeer's)

thank you Glinzek for adding clarity ... it is a muddled subject with many interpretations

Answer 2

Toutvas is pretty much on the money with his answer.

The boundaries between the different genres do get muddied up somewhat. Mozart's "Magic Flute" is almost always referred to as an opera, though due to the volume of spoken dialogue it falls into the category of Singspiel, while
you could call "Les Miserables", the popular musical, an opera because there is no spoken dialogue in the entire show. I would have a hard time arguing with that, even though the quality of the music would normally not be classified as "operatic".

The term "operetta" has always confused me. If "The Mikado" were written and staged today, it would probably be called a musical.

Answer 3

The classic American musical is in a line descending from the operettas of Johann Strauss II, Franz Lehar and Oscar Straus. This could be differentiated from 'grand opera' by the fact that they have a great deal of spoken word, rather than accompanied recitatives. The operettas, in their turn, had descended from the German and Austrian 'singspiels', or plays with music. In fact, Mozart's 'Magic Flute' is an example of singspiel. At the most basic all these forms were designed to be more populist. Most opera was designed for the aristocracy and upper reaches of society. Nowadays, it is quite easy to decide what genre a particular work falls into. Or is it? Is West Side Story an opera with spoken dialogue or an operetta or an opera? And I haven't even begun to disuss the Spanish genre of lighter musical stories called 'zarzuelas'

Answer 4

That is a REALLY good question.
Barring the thought that there might be an official difference that I am not aware of, I think the difference lies in the kind of music. Operetic music is classical music, whereas musicals for the most part are pop music in varying degrees and styles.
In saying that, the operas in their time were considered popular entertainment - as musicals are considered today, so maybe there is no difference at all!

Answer 5

Operas make you fall asleep
Musicals (some of them) can be enjoyable
My favorite musicals are: 7 Brides for 7Brothers (Yea, I know, I'm old) and Grease.

Answer 6

Opera is sung in an operatic style of song.

Musical script is a mixture of spoken words and songs where as opera is all song.

Musicals often incorporate dance where as opera is sung and acted out.