What is the difference between opera and oratorio?

Question: What is the difference between opera and oratorio?

Answer:

New Groves Dictionary of Music and Musicians defines oratorio as “an extended musical setting of a sacred text made up of dramatic, narrative and contemplative elements.” Unlike opera, oratorios are never staged.

Howard E. Smither: 'Oratorio', Grove Music Online ed. L. Macy (Accessed 30 July 2004), <http://www.grovemusic.com>

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