What is the difference between 'Group' mode and 'Surround' mode?

Group mode is used to play the same song to multiple Wireless Audio 360 systems in different rooms.

Surround is used to configure a multi-channel system with multiple speakers in a room so that you can experience immersive surround sound.

For example: If you have two sets of R7, you can arrange them to play 2Ch stereo. You can even create 4.1Ch surround sound with two RC7s and a compatible Samsung soundbar.