What is a concerto based on the opposition of small and large groups of instruments is called?

A concerto based on the opposition of small and large groups of instruments is called a "concerto grosso." This form typically contrasts a small group of soloists, known as the concertino, with a larger ensemble, called the ripieno or tutti. The concerto grosso was particularly popular during the Baroque period and is characterized by its dynamic interplay between the two groups. Notable composers of this form include Arcangelo Corelli and Antonio Vivaldi.