Answer:
Opera buffa is a genre of opera first used as an informal description of Italian comic operas classified by their authors as "comedia in musica", "comedia per musica", "dramma bernesco", "dramma comico", "giocoso fun" ", etc. associated with developments in Naples in the first half of the 18th century, from where its popularity spread to Rome and northern Italy. Initially, it was characterized by daily settings, local dialects and simple vocal writing, the main requirement being clear diction and ease with the pattern.
Opera seria is a genre of opera that refers to the royal and considered serious style of Italian opera that most apeared in Europe from the 1710s to c. 1770. The term itself was rarely used at the moment and only reached common usage, since opera would be running out of fashion and beginning to be seen as a historical genre. The opera's popular rival was opera buffa, the "comic" opera that led to the suggestion of the improvised comedy dell'arte.