What is the difference between a jazz band and a jazz orchestra?

A jazz band typically refers to a smaller ensemble, often consisting of a rhythm section (piano, bass, drums) and a few horns, focusing on improvisation and individual expression. In contrast, a jazz orchestra, or big band, is larger, usually featuring multiple sections of brass and woodwinds, and emphasizes arranged music alongside improvisation. The orchestration allows for more complex harmonies and arrangements, creating a fuller sound. Overall, the primary difference lies in size, instrumentation, and the emphasis on arrangements versus improvisation.