Polyphony and chorus both refer to the way multiple voices or singers sing at the same time, but they have some differences in music.

Polyphony refers to multiple independent voices or instruments playing or singing different melodies at the same time, and these melodies together form a whole. In polyphonic music, each voice has its own melody line, and they can be independent, intertwined, or counterpointed. Polyphonic music is commonly found in classical music, such as the fugues of the Baroque period and the suites of Bach.

Choir refers to a group composed of multiple singers singing the same song or musical work at the same time. Singers in a choir are usually divided into different voices, such as soprano, baritone, bass, etc. The singing relationship between the parts of a choral work is usually coordinated to create a harmonious overall sound effect. Choral music is widely used in religious worship, music performances and community cultural activities, such as religious choirs, choir singing and choral competitions.

To sum up, polyphony refers to multiple voices playing or singing different melodies at the same time, while chorus refers to a group composed of multiple singers singing the same song or musical work at the same time. They have certain differences in musical form and singing methods.