The word choir (or quire) means not only the group of singers, but also the area between the rood screen and the nave where the singers are often placed.
If you’ve seen pictures of English royal weddings or funerals at Westminster Abbey, you may have noticed the facing pews with little lamps above each place. That’s the choir. The singers are also the choir.
The chancel includes the choir and the area closer to the altar, sometimes marked off by a communion rail. This is where the clergy and assisting ministers carry out their work during worship.