There are a few key differences between a 5.1 and 2.1 sound bar that are worth noting. Firstly, a 5.1 sound bar will have five channels of audio output, whereas a 2.1 sound bar will only have two. This means that the 5.1 sound bar is capable of delivering surround sound, whereas the 2.1 sound bar is not. Additionally, the 5.1 sound bar will typically come with a subwoofer, which the 2.1 sound bar will not. This means that the bass response of the 5.1 system will be much better than that of the 2.1 system. Finally, the price tag for a 5.1 system will be significantly higher than that of a 2 .