There are some semi-strict definitions. From my favorite go-to ,
the ripresa, ritornello, and passacaglia are based on the 16th-century
Italian dance form. The ripresa or ritornello (often appearing as V-I
or IV-V-I) is a unit of music that precedes, follows, or alternates
with a dance. The internal ripresa could be used as a portion within a
I'd say the main difference between rondo and ritornello is one of emphasis. In a typical rondo, the 'refrain' carries the main musical interest or idea, with the 'couplets' providing relief and variety between its repetitions.
In a baroque concerto allegro, on the other hand, the ritornello tends to serve as a brief 'appetizer' or 'motto' for the more ...