The difference between a 5.1 and a 7.1-channel system is that there are two more speakers in a 7.1-channel. You can easily figure this out by the first digit as it refers to the number of speakers that will come with the system. For a 5.1-channel system, you’ll get five speakers to go along with a subwoofer, which is denoted by the .1. There will be seven speakers in the 7.1-channel system along with a subwoofer with that as well. The extra speakers that come in a 7.1-channel are usually placed at the rear listening position and are often referred to as surround rear speakers.