MULTIROOM - or PARTY MODE
Party Mode is a feature that lets you listen to the same song on various connected products, fully synchronized across all of them. For example, you can stream one song on up to 10 connected devices.
Multi-Zone is a feature that lets you play different songs to different speakers/adapters. For example you can play 10 different songs to 10 different connected audio devices, or play 1 song to up to 10 different connected devices. . Or, you could play one song to four devices and another song to the remaining six devices. You get to be the DJ in your home.