I have a tradition of listing to Bach's "Mass in B minor" around springtime of each year, as I was once part of a chorus-ensemble that performed it a number of years ago.

My wife doesn't have much technical training in music (not that I have all that much myself). Often, and especially during the soloist bits of the mass, she'll ask me if I'm listening to an opera. It occurred to me that operas are probably more familiar in the popular imagination than an orchestral/choral work like "Mass in B minor." And when an untrained ear hears a polished soloist singing with vibrato, I suppose it's common to think you're listening to an opera?

But I find myself at a loss for how to describe to her the difference between an opera and a work like a mass. I know operas are more narrative-driven than a Latin mass, but musically (and especially vocally), how is a Baroque work like "Mass in B minor" any different than an opera?

  • 1
    Keep in mind music for the mass ranges from Gregorian chant to modern styles like Janacek's Glagolitic Mass. Mar 2, 2022 at 20:15
  • @MichaelCurtis and opera's musical styles are more limited only because opera was invented a millennium or so later than the mass.
    – phoog
    Mar 3, 2022 at 21:49

4 Answers 4


There are several layers of distinction here. Your wife (and many others) are mainly aware of a difference in vocal style; this is simply a difference between the style used in "classical" "art" music and other modern genres.* It might sound less like opera, by the way, if you listen to a recording that is grounded in historic performance practice; much of the bel canto technique that we associate with opera arose in the 19th century, well after Bach's time. In this recording with the Freiburg Baroque Orchestra and St. Thomas Boys' Choir, the vocal style would still not be mistaken for modern pop, but lacks the wide vibrato and powerful projection that people associate with Bugs Bunny in a Brunhilde costume:

(Note, opera itself is much older than modern operatic technique; opera was big business—show business—long before Bach. The technique of the 17th century is a matter of much research and conjecture, but it certainly wasn't Wagnerian; it's not a matter of "historic baroque style vs operatic style.")

As for what makes a mass, as a type of work, different from an opera, let's answer a different question first: what makes an oratorio different from an opera? The most famous oratorio is easily Handel's Messiah, but it's a bit of an atypical example. Take a different Handel oratorio then, Israel in Egypt. Like an opera, it has a storyline. It has characters, sung by various soloists. It has a chorus for the "big numbers." What it lacks is staging—no costumes, no scenery, no walking around the stage.

So what makes a mass different than an oratorio? This is a bit like asking "what makes a church service different than a Broadway show." A mass is a religious service. Its format has been in place for centuries (with slight tweaks), with components still referred to in Latin (and Greek)—the Kyrie, the Gloria, the Credo. A musical composition that calls itself a mass simply sets these liturgical texts to music.

* This is because, when people encounter an unfamiliar culture, they're at first highly aware of how it differs (as a whole) from familiar cultures, and not aware of differences within the culture. For instance, to Western listeners with little experience of Indian music, it's hard to notice the differences between different ragas and talas; it all "sounds the same" because they're too aware of the characteristics that are common to all the Indian examples but not to Western music: drone, certain timbres of plucked strings, instrumentation, etc.

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    I would like to add that contemporary critics complained that both Bach's and Haydn's religious music was "too operatic."
    – ttw
    Mar 2, 2022 at 21:38
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    Side note: the kyrie is Greek, if I’m not mistaken. Mar 3, 2022 at 3:22

For many people who have no real concept of classical music anything with singing is often classified as "opera", probably as that is the most know example of such a thing.

The elephant in the room: An opera is a staged work, while a mass isn’t. An opera follows any kind of narrative while a mass is bound to the liturgical choreography of a christian mass. Most masses thus consist of very common parts from the Ordinario (Kyrie, Gloria, Credo, Sanctus & Benedictus, Agnus Dei). Other masses change the text but often follow the message.

Musical differences:

  • The orchestra: operas tend to have bigger and more complex orchestras
  • The singers: operas tend to be focussed around soloist, while masses tend to be centered around choirs with a small amount of soloists (usually one per voice type)
  • The structure: Masses have a loose structure of unconnected pieces, while in operas the composition of pieces follows a connected narrative.

That are some characteristics, but it is not hard to find more.

  • Also the language. Most masses are in Latin. I’m not sure if any operas are at all, but of course Italian and German are very common for classical operas. Mar 3, 2022 at 1:57
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    @ToddWilcox Look up Oedipus rex by Stravinsky.
    – Lazy
    Mar 3, 2022 at 7:00

The basic characteristic of a Mass is that - well - it IS a Mass. A musical setting of a religious service. The classic form consists of five sections, Kyrie, Gloria, Credo, Sanctus, Agnus Dei. Musical style is completely up for grabs, though it will obviously tend towards the reverent or triumphant rather than the jocular! But it's only the text that can really make you sure that your listening to Mozart's Requiem Mass rather than one of his less flippant operas, Verdi's Requiem Mass rather than his opera 'Nabucco.

  • I think comparing Mozart's and Verdi's sacred versus similar secular examples really makes the point clear, it's a matter of the text. Mar 3, 2022 at 13:38

A mass has the standard sequence as described by LaurencePayne. Note, that most masses are by far too extensive to be performed in church embedded in the standard service. Sometimes just the church organ is required for the instrumental part.

An opera has a plot (synopsis, libretto) and singers representing the persons involved. The orchestra required ranges from small (baroque opera) to very big. (Richard Wagner).

Unfortunately there are additional genres blurring the picture:

  • Passions, which describe the suffering of Jesus and his death on the cross.
  • Oratorios. These were considered as acceptable even during times when opera was frowned upon; Handel wrote quite a number of those, which are mostly operas but take their plot from the bible. Bach's Easter oratorio is a different type which is more like a cantata, see below.
  • Cantatas: church music written for a certain date in ecclesiastical year.

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